Measurement of fractional order model parameters of respiratory mechanical impedance in total liquid ventilation

This study presents a methodology for applying the forced-oscillation technique in total liquid ventilation. It mainly consists of applying sinusoidal volumetric excitation to the respiratory system, and determining the transfer function between the delivered flow rate and resulting airway pressure. The investigated frequency range was f ∈ [0.05, 4] Hz at a constant flow amplitude of 7.5 mL/s. The five parameters of a fractional order lung model, the existing "5-parameter constant-phase model," were identified based on measured impedance spectra. The identification method was validated in silico on computer-generated datasets and the overall process was validated in vitro on a simplified single-compartment mechanical lung model. In vivo data on ten newborn lambs suggested the appropriateness of a fractional-order compliance term to the mechanical impedance to describe the low-frequency behavior of the lung, but did not demonstrate the relevance of a fractional-order inertance term. Typical respiratory system frequency response is presented together with statistical data of the measured in vivo impedance model parameters. This information will be useful for both the design of a robust pressure controller for total liquid ventilators and the monitoring of the patient's respiratory parameters during total liquid ventilation treatment.     

Petroleum hydrocarbon biodegradation under seasonal freeze-thaw soil temperature regimes in contaminated soils from a sub-Arctic site

Several studies have shown that biostimulation in ex situ systems such as landfarms and biopiles can facilitate remediation of petroleum hydrocarbon contaminated soils at sub-Arctic sites during summers when temperatures are above freezing. In this study, we examine the biodegradation of semivolatile (F2: C10-C16) and nonvolatile (F3: C16-C34) petroleum hydrocarbons and microbial respiration and population dynamics at post- and presummer temperatures ranging from -5 to 14 °C. The studies were conducted in pilot-scale tanks with soils obtained from a historically contaminated sub-Arctic site in Resolution Island (RI), Canada. In aerobic, nutrient-amended, unsaturated soils, the F2 hydrocarbons decreased by 32% during the seasonal freeze-thaw phase where soils were cooled from 2 to -5 °C at a freezing rate of -0.12 °C d(-1) and then thawed from -5 to 4 °C at a thawing rate of +0.16 °C d(-1). In the unamended (control) tank, the F2 fraction only decreased by 14% during the same period. Biodegradation of individual hydrocarbon compounds in the nutrient-amended soils was also confirmed by comparing their abundance over time to that of the conserved diesel biomarker, bicyclic sesquiterpanes (BS). During this period, microbial respiration was observed, even at subzero temperatures when unfrozen liquid water was detected during the freeze-thaw period. An increase in culturable heterotrophs and 16S rDNA copy numbers was noted during the freezing phase, and the (14)C-hexadecane mineralization in soil samples obtained from the nutrient-amended tank steadily increased. Hydrocarbon degrading bacterial populations identified as Corynebacterineae- and Alkanindiges-related strains emerged during the freezing and thawing phases, respectively, indicating there were temperature-based microbial community shifts.     

Responses of milk fat composition to dietary fat or nonstructural carbohydrates in Holstein and Jersey cows

Milk fat from Jersey cows contains less oleic acid (cis-C18:1) and more short- and medium-chain fatty acids than does milk fat from Holstein cows. The objective of this experiment was to determine responses in milk fat composition when Jersey and Holstein cows were fed diets either high (37% of dry matter) or low (27% of dry matter) in content of nonstructural carbohydrates (NSC) and supplemented with either 0 or 2.5% (of dry matter) of a mostly saturated fat source. Four Holstein cows and four Jersey cows were used in a Latin square design with 28-d periods; diets were in a 2 x 2 factorial arrangement. Fat supplementation decreased contents of fatty acids synthesized de novo within the mammary gland and increased contents of C18:0 and cis-C18:1. Low-NSC diets tended to increase C16:0 and to decrease C18:0, cis-C18:1, and C18:3. Despite the differences in fatty acid composition between breeds, both breeds generally responded similarly to dietary treatments. An interaction of breed and fat indicated that the content of cis-C18:1 in milk fat was increased more by supplemental fat in Holsteins than in Jerseys. Interactions of breed x fat and breed x carbohydrate type showed that the ratio of cis-C18:1 to C18:0 decreased when Jerseys were supplemented with fat but increased for Holsteins, and decreased when Jerseys were fed the low-NSC diet but increased when Holsteins were fed low NSC. The data are consistent with the hypothesis (Beaulieu and Palmquist, 1995, J. Dairy Sci. 78:1336-1344) that mammary activity of stearoyl-coenzyme A desaturase is lower in Jerseys than in Holsteins.     

A comparison of SNR estimation techniques for the AWGN channel

The performances of several signal-to noise ratio (SNR) estimation techniques reported in the literature are compared to identify the "best" estimator. The SNR estimators are investigated by the computer simulation of baseband binary phase-shift keying (PSK) signals in real additive white Gaussian noise (AWGN) and baseband 8-PSK signals in complex AWGN. The mean square error is used as a measure of performance. In addition to comparing the relative performances, the absolute levels of performance are also established; the simulated performances are compared to a published Cramer-Rao bound (CRB) for real AWGN and a CRB for complex AWGN that is derived here. Some known estimator structures are modified to perform better on the channel of interest. Estimator structures for both real and complex channels are examined.     

Effects of indoor drinking water handling on trihalomethanes and haloacetic acids

In this study, different tap water handling strategies were investigated to evaluate the effects on two principal chlorinated DBPs, trihalomethanes (THMs) and haloacetic acids (HAAs). Tap water samples collected in the Quebec City (Canada) distribution system on a spatio-temporal basis were subjected to diverse indoor handling scenarios: storing water in the refrigerator, boiling water followed by storage and, finally, filtering water with a point-of-use commercial pitcher also followed by storage. In the first two cases, the use of covered and uncovered pitchers was investigated separately, while in the last case, both the use of new and used filters was compared. In all cases, maximum storage time was 48h. Results demonstrated that in some cases, water handling scenarios have considerable effect, and in other cases, little or no effect. Removal of THM concentrations by simple storage was high (on average 30%) and very high by boiling and filtering with subsequent storage in the refrigerator (on average, 87% and 92%, respectively). In scenarios where water was stored in uncovered pitchers (with or without previous boiling and filtering), the THM decrease was higher for increased storage times. However, storage did not have any effect on HAAs, whereas boiling decreased levels of trichloroacetic acid (TCAA) (on average 42%) and increased levels of dichloroacetic acid (DCAA) (on average 35%), resulting in unchanged average levels of total HAAs. The use of the filtration pitcher decreased HAA levels dramatically (on average 66%). Percentages of change in chlorinated DBPs in the different scenarios varied according to initial concentrations in tap water (baseline water), that is, according to the spatio-temporal variations of these substances in the distribution system. On the basis of these results, the paper discusses implications regarding public health protection and exposure assessment for epidemiological studies.     

A “better than” Nyquist pulse

A novel ISI-free pulse is presented that has smaller maximum distortion, a more open receiver eye, and a smaller probability of error in the presence of symbol timing error than the Nyquist pulse for the same excess bandwidth     

Hierarchy in picture segmentation: a stepwise optimization approach

A segmentation algorithm based on sequential optimization which produces a hierarchical decomposition of the picture is presented. The decomposition is data driven with no restriction on segment shapes. It can be viewed as a tree, where the nodes correspond to picture segments and where links between nodes indicate set inclusions. Picture segmentation is first regarded as a problem of piecewise picture approximation, which consists of finding the partition with the minimum approximation error. Then, picture segmentation is presented as an hypothesis-testing process which merges only segments that belong to the same region. A hierarchical decomposition constraint is used in both cases, which results in the same stepwise optimization algorithm. At each iteration, the two most similar segments are merged by optimizing a stepwise criterion. The algorithm is used to segment a remote-sensing picture, and illustrate the hierarchical structure of the picture     

Differential expression of two major cytokines produced by neutrophils, interleukin-8 and the interleukin-1 receptor antagonist, in neutrophils isolated from the synovial fluid and peripheral blood of patients with rheumatoid arthritis

OBJECTIVE: Neutrophils have been shown to produce interleukin-8 (IL-8) and interleukin-1 receptor antagonist (IL-1ra) in large amounts compared with other cytokines. Since IL-8 has a proinflammatory action whereas IL-1ra is antiinflammatory, our objective was to examine the relative levels of production of these cytokines by synovial fluid (SF) neutrophils isolated from patients with rheumatoid arthritis (RA). METHODS: We measured cytokine production using an enzyme-linked immunosorbent assay and analyzed messenger RNA accumulation in cells by Northern blot. RESULTS: SF neutrophils produced significantly more IL-8 and IL-1 beta, but significantly less IL-1ra, than peripheral blood neutrophils. CONCLUSION: These observations provide new information on the production of pro- and antiinflammatory molecules by neutrophils in the SF environment, and their possible role in RA.     

White-light interferometric fiber-optic pressure sensor

A novel configuration for a fiber-optic white-light interferometric sensor is presented which allows for absolute measurements of hydrostatic pressure with an improved operation range. The performance of two fibers (York bow-tie 800 and especially designed elliptical-core side-hole fiber) used as sensing elements was experimentally studied. The sensor itself was composed of two equal lengths of the fiber spliced at 90°. This structure assures temperature compensation and enables application of a Wollaston prism as a receiving interferometer. A step delay line made of crystalline quartz was used to increase the operation range of the sensor