Air/Water Oxygen Transfer in a Biological Aerated Filter

The oxygen-transfer characteristics of an upflow biological aerated filter filled with angular clay media were determined over a wide range of gas and liquid flow rates. Liquid-side, oxygen-transfer coefficients (KLa) were measured using a nitrogen gas stripping method under abiotic conditions and were found to increase as both gas and liquid superficial velocity increases, with values ranging from 12 to 110?h?1 based on empty bed volume. The effect of gas and liquid velocity, wastewater to clean water ratio, and temperature dependence was correlated to within ±20% of the experimental KLa value. Stagnant gas holdup is roughly double in wastewater compared to clean water, but the dynamic gas holdup is the same. The oxygen-transfer coefficient is directly proportional to the dynamic gas holdup. Stagnant gas holdup does not influence the rate of oxygen transfer. The results suggest that dynamic gas holdup largely determines the specific interfacial area (a), whereas the interstitial liquid velocity largely controls the oxygen-transfer coefficient (KL).     

A multiple-scale analysis of grating-assisted couplers

Optical directional couplers with longitudinal periodic perturbations or gratings are analyzed by a multiple-scale solution to the coupled-mode equations. The use of two length scales in the analysis becomes the key to obtaining globally valid analytic solutions, which are shown to be in excellent agreement with the exact numerical solutions. Because of the nonorthogonality of the coupled modes in the structure, two different coupling lengths, a maximum power transfer length and a zero crosstalk length, are predicted for the power exchange. The spectral properties of the coupler are also studied through a generalized multiple scale method     

Assessment of strain gradients affecting the performance of 3-D strain rosettes – relevant to the analysis of cement mantle strains in total hip replacements

A large scale model analysis, using embedded strain gauges, of the strain distribution in the cement mantle surrounding a femoral prosthesis is underway. In order to predict, and so avoid, positions of locally high strain gradients in this model, a finite element and experimental analysis of a similar problem was undertaken. For this purpose, a loose fitting rectangular steel insert inside a surrounding rectangular epoxy sheath was used to model an extreme case of the torsional and bending components of hip joint load. The axial component of joint load was modelled using an axisymmetric finite element model of a tapered shaft. The finite element results were used to determine suitable positions for embedding gauges in the experimental model. Results showed that the finite element analysis failed to adequately model the close sliding fit between the steel insert and epoxy. Altering the experimental model to artificially replicate the finite element contact conditions produced good correlation in bending, with experimental strains agreeing with simple bending theory to within 6%. Satisfactory correlation under torsional loading was not obtained, but strain magnitudes were low. Predicted positions for embedding gauges give conservative results, lessening the possibility of strain gradient induced error in the large scale model test of the cement mantle and prosthesis.     

Assignments of meaning in epidemiology

Epidemiology works in a public domain, gathering the results of surveys and trials into forms of knowledge which are made available to many stakeholders. Health policy makers, lawyers, the media, medical technology companies, and those who use and deliver health services all have legitimate interests in epidemiology. There is unfortunately no common language in which each of these stakeholders can express their interest in the outcomes of epidemiological studies. The largest and most important gap exists between those who use computational data and those who use cultural and linguistic models to generate their explanations. Methods have been described, however, which allow the identification of all legitimate stakeholders before epidemiological studies are undertaken. Identifying the stakeholders, however, will serve no purpose unless there is a prior commitment by epidemiologists to respect both reductionist and narrative accounts of truth.     

Automatic composition techniques for video production

Video production involves the process of capturing, editing and composing video segments for delivery to a consumer. A composition must yield a coherent presentation of an event or narrative. This process can be automated if appropriate domain-specific metadata are associated with video segments and composition techniques are established. Automation leads to the support of dynamic composition and customization for applications such as news on demand. In this paper, we present techniques to achieve dynamic, real-time and cohesive video composition and customization. We also identify metrics for evaluating our techniques with respect to existing manually produced video-based news. The results of such an evaluation show that the quality of automatic composition is comparable to-and in some cases, better than-broadcast news video composition. The results also validate the assertions on which the automatic composition techniques are based     

GP documentation of obesity: what does it achieve?

BACKGROUND: Obesity is a major and increasing health problem in the United Kingdom, and, until recently, the government health promotion package for general practice reimbursed general practitioners for documenting obesity. Despite poor evidence for effectiveness of interventions in primary care, documentation of obesity could possibly improve patient awareness and knowledge, or provide public health information. AIM: To assess patient perception of obesity and its health risk, and the accuracy of estimating obesity using patient information. METHOD: Subjects were consecutive attenders to a general practitioner (GP) at a single urban practice in the South and West Region. Outcome measures were 'measured' body mass index (BMI) calculated from measured weight and height, 'estimated' BMI using patient information, and patient perception of obesity and the health risks of obesity. RESULTS: There is good correlation between 'estimated' and 'measured' BMI (intraclass correlation 0.91). Estimated BMI is lower than measured BMI (mean 0.77 lower), and the difference increases with age and level of BMI: for BMIs of < 20, 20-24.99, 25-29.99, and > or = 30 the mean differences (estimated-measured) were -0.06, -0.46, -0.98 and -1.72 respectively. Estimated obesity (BMI > 30) is reasonably sensitive (70%), specific (99%), and predictive (93% positive predictive value) of measured obesity (kappa 0.78). All obese subjects are aware that they are overweight, and most of them (78%, 95% confidence interval 66-88%) are aware that their weight is a health risk. CONCLUSION: Obese patients attending GPs' surgeries are likely to know if they are overweight, or could easily estimate from their knowledge of height and weight that they were overweight with reasonable accuracy. Obese subjects also know that their weight carries health risks. Thus, measurement of obesity in the general population is not likely to improve risk assessment or patient knowledge significantly. Without evidence for effective intervention or improved decision-making in primary care, reimbursement guidelines linked to the documentation of obesity in the population are probably an inefficient use of resources.     

Molecular typing shows a high level of HLA class I incompatibility in serologically well matched donor/patient pairs: implications for unrelated bone marrow donor selection

In comparison with HLA-matched sibling bone marrow transplants, unrelated donor transplants are associated with increased graft-versus-host disease and graft failure. This is likely in part due to HLA incompatibilities not identified by current matching strategies. High resolution DNA-based typing methods for HLA class II loci have improved donor selection and treatment outcome in unrelated donor bone marrow transplantation. By using DNA-based typing methods for HLA-A and -B on a cohort of 100 potential bone marrow donor/patient pairs, we find that serological typing for HLA class I is limited in its ability to identify incompatibilities in unrelated pairs. Furthermore, the incompatibilities identified are associated with the presence at high frequency of alloreactive cytotoxic T-lymphocyte precursors. DNA typing also indicates that HLA-C mismatches are common in HLA-A and -B serologically matched pairs. Such mismatches appear to be significantly less immunogenic with respect to cytotoxic T-lymphocyte recognition, but are expected to influence natural killer cell activity. Thus, improved resolution of HLA class I shows many previously undisclosed mismatches that appear to be immunologically functional. Use of high resolution typing methods in routine matching is expected to improve unrelated donor selection and transplant outcome.     

Memory-enhancing effects of secreted forms of the beta-amyloid precursor protein in normal and amnestic mice

When administered intracerebroventricularly to mice performing various learning tasks involving either short-term or long-term memory, secreted forms of the beta-amyloid precursor protein (APPs751 and APPs695) have potent memory-enhancing effects and block learning deficits induced by scopolamine. The memory-enhancing effects of APPs were observed over a wide range of extremely low doses (0.05-5,000 pg intracerebroventricularly), blocked by anti-APPs antisera, and observed when APPs was administered either after the first training session in a visual discrimination or a lever-press learning task or before the acquisition trial in an object recognition task. APPs had no effect on motor performance or exploratory activity. APPs695 and APPs751 were equally effective in the object recognition task, suggesting that the memory-enhancing effect of APPs does not require the Kunitz protease inhibitor domain. These data suggest an important role for APPss on memory processes.     

Altered inotropic response of endothelin-1 in cardiomyocytes from rats with isoproterenol-induced cardiomyopathy

Retrograde transport from the Golgi to the ER is an essential process. Resident ER proteins that escape the ER and proteins that cycle between the Golgi and the ER must be retrieved. The interdependence of anterograde and retrograde vesicle trafficking makes the dissection of both processes difficult in vivo. We have developed an in vitro system that measures the retrieval of a soluble reporter protein, the precursor of the yeast pheromone alpha-factor fused to a retrieval signal (HDEL) at its COOH terminus (Dean, N., and H.R.B Pelham. 1990. J. Cell Biol. 111:369-377). Retrieval depends on the HDEL sequence; the alpha-factor precursor, naturally lacking this sequence, is not retrieved. A full cycle of anterograde and retrograde transport requires a simple set of purified cytosolic proteins, including Sec18p, the Lma1p complex, Uso1p, coatomer, and Arf1p. Among the membrane-bound v-SNAP receptor (v-SNARE) proteins, Bos1p is required only for forward transport, Sec22p only for retrograde trafficking, and Bet1p is implicated in both avenues of transport. Putative retrograde carriers (COPI vesicles) generated from Golgi-enriched membranes contain v-SNAREs as well as Emp47p as cargo.