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61.
A framework for analyzing the performance of coded OSTBC-OFDM systems over arbitrary correlated generalized Ricean fading channels is established. The moment generating function of the signal-to-noise ratio at the input to the channel decoder is derived assuming correlated transmitter and receiver antennas and correlated paths in frequency selective channels. The probability of outage, the pairwise error probability, and the bit error rate are then evaluated. Bit-interleaved and iteratively decoded turbo product codes, Gray encoded M-ary quadrature amplitude modulation, and other parameters of the IEEE 802.16 Standard are used to illustrate numerical results. 相似文献
62.
The performances of two signal-/?/wi-noise (S + N) selection diversity receivers employing noncoherent M-ary frequency shift keying (MFSK) in slow, flat, correlated Rayleigh and Rician fading channels are examined. The branches are assumed to be equally correlated for Rician fading. The correlation model for Rayleigh fading is more general than the equally correlated scenario and includes it as a special case. Analytical expressions are derived for the average symbol error rate (SER) and the average bit error rate (BER) of each receiver structure. Extensive Monte Carlo simulation results are presented to validate the analytical expressions. The performances of the S + N SC receivers are compared to the performance of the classical SC receiver. The effects of correlation, average fading power imbalance and diversity order on the performances of the S + N SC receivers are examined. 相似文献
63.
Lowry MI Bartelt-Hunt SL Beaulieu SM Barlaz MA 《Environmental science & technology》2008,42(19):7444-7451
Models describing the behavior of organic chemicals in landfills can be useful to predict their fate and transport and also to generate input data for estimates of exposure and risk. The landfill coupled-reactor (LFCR) model developed in this work simulates a landfill as a series of fully mixed reactors, each representing a daily volume of waste. The LFCR model is a numerical model allowing time-variable input parameters such as gas generation, and cover type and thickness. The model was applied to three volatile organic chemicals (acetone, toluene, benzene) as well as naphthalene and the chemical warfare agent sarin under three landfill conditions (conventional, arid, bioreactor). Sarin was rapidly hydrolyzed, whereas naphthalene was largely associated with the landfill solid phase in all scenarios. Although similar biodegradation rates were used for acetone and toluene, toluene was more persistent in the landfill due to its hydrophobicity. The cover soil moisture content had a significant impact on gaseous diffusive losses. 相似文献
64.
M. Juárez M.E.R. Dugan N. Aldai J.L. Aalhus J.F. Patience R.T. Zijlstra A.D. Beaulieu 《Food chemistry》2011
To clarify the impact of feeding co-extruded flaxseed on carcass quality and pork palatability, 96 pigs (48 barrows and 48 gilts) were fed three different levels of flaxseed (0%, 5% and 10% of dietary intake) for 76 days. Carcass quality and meat quality characteristics of pure loin muscle and ground pork (20% fat) were evaluated. Fat hardness and belly firmness decreased (P < 0.001) with increasing co-extruded flaxseed. Pigs fed co-extruded flaxseed levels had higher lean yield (P = 0.045) and total lean content (P = 0.034). Loin from barrows had higher fat content compared to gilts (P < 0.001). Co-extruded flaxseed supplementation increased (P < 0.001) omega-3 content in loin and ground pork. Pork flavour intensity and off-flavour intensity scores lowered (P < 0.001) with increasing levels of co-extruded flaxseed, being more accentuated (P = 0.023) in reheated pork chops from barrows. Diet affected all texture and flavour sensory characteristics (P < 0.05) as tissue levels of omega-3 fatty acids increased, likely as a result of increased lipid oxidation. 相似文献
65.
E Busch C Beaulieu A de Crespigny ME Moseley 《Canadian Metallurgical Quarterly》1998,29(10):2155-2161
BACKGROUND and PURPOSE: We analyzed the temporal and spatial pattern of water diffusion changes during acute subarachnoid hemorrhage (SAH) in rat brain to identify factors contributing to the acute pathophysiology of SAH. METHODS: Subarachnoid hemorrhage was remotely induced via perforation of the circle of Willis with an endovascular suture during MR imaging. A fast echo-planar imaging technique was used to acquire 60 maps of the apparent diffusion coefficient (ADC) beginning 1 min before and continuing for 11 min after induction of SAH. A high-resolution spin-echo diffusion sequence was used to follow diffusion changes over 6 h after SAH. Sham-operated control (n=3), nonheparinized (n=6), and heparinized (n=5) groups were studied. RESULTS: Sham-operated control animals did not show ADC changes over time. In both SAH groups, however, a sharp decline of ADC within 2 min of SAH was consistently observed in the ipsilateral somatosensory cortex. These decreases in diffusion then spread within minutes over the ipsilateral hemisphere. Similar ADC decreases on the contralateral side started with a further time delay of 1 to 3 min. From 30 min onward, the extent of the diffusion abnormality decreased progressively in the nonheparinized animals. No recovery was observed in heparinized rats. CONCLUSIONS: MR diffusion imaging allows new insight into the pathophysiology of acute SAH: The spatial and temporal pattern of diffusion changes suggests the initial occurrence of acute vasospasm and subsequently "spreading depolarization" of brain tissue. Persistent hemorrhage in heparinized animals was reflected by early decline of ADC values throughout the entire brain. 相似文献
66.
The variations of the limiting flux during skimmed milk ultrafiltration were studied under various physicochemical environments (pH, ionic strength, chemical nature of added salts). The evolutions were explained taking into account the physicochemical characteristics (size distribution, zeta potential) of the casein micelles, that is the main components of the fouling layer formed at the membrane surface. It was shown than in the pH range from 5.6 to 6.7, the limiting flux was linearly related to the zeta potential of the casein micelles regardless of the way used to obtain the zeta potential variation (addition of HCl, CaCl2 or NaH2PO4): the higher the zeta potential of casein micelles (neutral pH), the greater the limiting flux. Under these operating conditions, the variations of hydrophobic interactions were negligible. The variation of the permeability of the deposit layer, composed of retained casein micelles, was therefore mainly governed by electrostatic interactions due to the casein micelles. 相似文献
67.
Pageot LP Perreault N Basora N Francoeur C Magny P Beaulieu JF 《Microscopy research and technique》2000,49(4):394-406
The intestinal epithelium is continuously and rapidly renewed by a process involving cell generation, migration, and differentiation, from the stem cell population located at the bottom of the crypt to the extrusion of the terminally differentiated cells at the tip of the villus. Because of the lack of normal human intestinal cell models, most of our knowledge about the regulation of human intestinal cell functions has been derived from studies conducted on cell cultures generated from experimental animals and human colon cancers. However, important advances have been achieved over recent years in the generation of normal human intestinal cell models. These models include (a) intestinal cell lines with typical crypt cell proliferative noncommitted characteristics, (b) conditionally immortalized intestinal cell lines that can be induced to differentiate, and (c) primary cultures of differentiated villuslike cells that can be maintained in culture for up to 10 days. Each of these models should help in the investigation of the specific aspects of human intestinal function and regulation. Furthermore, taken together, these models provide an integrated system that allows an in vitro recapitulation of the entire crypt-villus axis of the normal human small intestine. 相似文献
68.
A. N. Spector Lay James Gibson Ashok K. Dutt William F. Hyde Paul B. Sherman Hans-Jurg Buttler Bernard Malamud Robert N. Anderson M. Penouil R. W. Keyes Lee R. McPheters William R. Eadington Kurt Puchinger Arthur E. Kartman Charles E. Starnes J. Barry Riddell Erick Sheppard Leon E. Zonn Craig Moore Neil S. Grigg K. Shimizu Daniel A. Griffith Noel D. Uri Micheal Ross Jack E. Adams Robert G. Fletcher Karol J. Krotki Peter D. Beaulieu Fred E. Case W. Edwin Derrick Barry D. Solomon Debnath Mookherjee John E. Keith Yuk Lee Andrew A. Dzurik W. W. Hall Jr. Lloyd W. Klemke Ted J. Adamczyk 《The Annals of Regional Science》1981,15(3):82-146
69.
A systematic empirical and analytical study was conducted to directly quantify the effect of enhanced ambient oxygen concentration on flame heat flux at bench scale and its ability to represent large-scale flame heat flux of well-ventilated fires. The Advanced Flammability Measurements Apparatus was used to conduct bench scale horizontal and single wall vertical orientation experiments for black polymethylmethacrylate, propylene gas and black polyoxymethylene. The key aspect of this study was direct experimental measurements of flame heat flux back to the burning surface for 20.9–40% ambient oxygen concentrations over a range of applied heat flux. The total flame heat flux, as well as the radiative and convective components, was experimentally measured with various gages. To gain more insight into the effects of oxygen, the flame emissivity, flame height and flame temperature were measured and used to calculate the radiative and convective components of the flame heat flux. Gas burner experiments were conducted to decouple the solid and gas phase effects of the ambient oxygen. Large scale tests of black polymethylmethacrylate were conducted in a horizontal orientation and literature data was used for single wall vertical orientations for comparison to the bench scale, enhanced oxygen results. The main conclusion is that the flame heat flux in enhanced ambient oxygen bench scale does not simulate large-scale flame heat flux in horizontal orientations but simulates a more severe large-scale geometry (parallel wall) in vertical orientations and is useful for evaluation of materials’ vertical flame spread potential. 相似文献
70.
C?té Sylvana M.; Borge Anne I.; Geoffroy Marie-Claude; Rutter Michael; Tremblay Richard E. 《Canadian Metallurgical Quarterly》2008,44(1):155
The authors examined the role of familial risk and child characteristics in the association between the type of child care in infancy (maternal care [MC]) versus nonmaternal care [NMC]) and emotional/behavioral difficulties at 4 years old. Canadian families (N=1,358) with children between 1 and 12 months old were followed over 4 years. Family risks were found to moderate the association between type of child care and physical aggression. MC in infancy was associated with lower levels of physical aggression among children from a low-risk family background but not among those from a high-risk family background. The effect size was small (d=-0.16; confidence interval [CI]=-0.3, -0.01). Family risk and the sex of the child moderated the association between child care and emotional problems. MC in infancy was associated with a lower level of emotional difficulties among girls from low-risk families but not among boys or among children from high-risk families. The effect size was moderate (d=-0.44; CI=-0.65, -0.23). The study indicates that the effect of child care type in infancy varies by family and child characteristics. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献