Multi-laboratory simulator studies on effects of serum proteins on PTFE cup wear

A multi-laboratory, simulator study investigated the wear of polytetrafluorethylene (PTFE) cups run in bovine serum. Each laboratory used its own test protocol with a variety of simulator types. Our wear model incorporated 32 mm dia CoCr heads matched to PTFE cups run with serum protein-concentrations in the range 17–69 mg/ml. The multi-lab data demonstrated that protein-concentration had the most significant effect on wear performance. Both inverted and anatomical cups followed the same trend with first a rapid increase in wear-rates apparent for the initially low-protein levels and then a wear-rate reduction effect becoming apparent beyond 17 mg/ml of proteins. The results showed that as the protein concentration increased from 17 to 69 mg/ml, the magnitude of the wear-rates increased 200% but the protein wear-rate gradient decreased 24–60% with “inverted” and “anatomical” cups, respectively. This effect was more pronounced with ‘anatomical” than “inverted” cups. Thus, the wear-trends with “inverted” cups were generally the more consistent, particularly at the low-protein levels. Increasing the serum volume by two-fold in one study increased the PTFE wear-magnitudes approximately 40% and the protein-wear gradient by 30%. These PTFE wear phenomena were consistent with the concept that low-concentrations of proteins promoted polymer wear but high-protein concentrations resulted in a protein-degradation phenomenon which progressively masked the actual polymer wear. In the selected protein range 17–69 mg/l, the multi-laboratory simulator data consistently overestimated the average clinical wear-rate by at least 50–100% depending on protein range. It would, therefore, appear clinically relevant to study PTFE wear with an inverted-cup model using a large volume of serum but only in low-protein concentrations. The protein-related wear phenomena observed with PTFE cups in this multi-laboratory project may also have relevance for wear-simulation of UHMWPE cups.     

A new algorithm for scansar processing

In this paper, a new phase preserving algorithm-the short IFFT algorithm for the burst-mode ScanSAR processing is presented. Analysis and simulation are done to verify the phase accuracy of this algorithm. Finally, the phase accuracy of this algorithm by making interferogram with simulated burst-mode INSAR data is illustrated. The results show that this new algorithm works well for interferometric application of ScanSAR data.     

Compensatory conviction in the face of personal uncertainty: Going to extremes and being oneself.

Study 1 participants' self-integrity (C. M. Steele, 1988) was threatened by deliberative mind-set (S. E. Taylor & P. M. Gollwitzer, 1995) induced uncertainty. They masked the uncertainty with more extreme conviction about social issues. An integrity-repair exercise after the threat, however, eliminated uncertainty and the conviction response. In Study 2, the same threat caused clarified values and more self-consistent personal goals. Two other uncertainty-related threats, mortality salience and temporal discontinuity, caused similar responses: more extreme intergroup bias in Study 3, and more self consistent personal goals and identifications in Study 4. Going to extremes and being oneself are seen as 2 modes of compensatory conviction used to defend against personal uncertainty. Relevance to cognitive dissonance and authoritarianism theories is discussed, and a new perspective on terror management theory (J. Greenberg, S. Solomom, & T. Pyszczynski, 1997) is proposed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Concreteness of relational effects on recall of adjective–noun pairs.

Studied the effects of concreteness and relatedness of adjective–noun pairs on free recall, cued recall, and memory integration. The authors report on 2 experiments in which Ss read phrases or sentences containing adjective–noun pairs that vary in rated concreteness and intrapair relatedness. In Exp 1 normative ratings on imagery and relatedness were provided by 23 graduate and 20 undergraduate students. 64 undergraduates participated in the memory experiment. Exp 2 extended Exp 1 by using complete sentences rather than adjective–noun word pairs. 72 undergraduates volunteered to participate in the memory experiment and a separate group of 14 volunteered to participate in a sentence rating task. Consistent with predictions from dual coding theory and prior results with noun–noun pairs, both experiments showed that the effects of concreteness were strong and independent of relatedness in free recall and cued recall. The 2 attributes also had independent (additive) effects on integrative memory as measured by conditionalized free recall of pairs. Integration as measured by the increment from free to cued recall occurred consistently only when pairs were high in both concreteness and relatedness. Relatedness, adjective imagery, and noun imagery ratings, along with word frequencies for adjectives and nouns, and sentences with relatedness ratings are appended. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The control of biofilms in tubes using wire‐wound inserts

As a possible alternative to the use of biocides in industrial water systems, studies have been made on the effectiveness of wire‐wound tube inserts for biofilm control. Comparisons of data obtained at two different empty tube velocities of 0.86 m/s and 1.27 m/s and a Reynolds number of 14 000 with and without inserts, show that a biofilm accumulation reduction approaching 50% can be achieved by the use of inserts under certain circumstances. Further work is required to establish the optimum design of insert for maximum effectiveness.     

Beneficial combination of wet oxidation,membrane separation and biodegradation processes for treatment of polymer processing wastewaters

The treatment of a model wastewater containing polyethylene glycol of molecular weight (MW) 10 000 by means of combined chemical oxidative pretreatment, membrane separation and biological post‐treatment was investigated. Wet oxidation was employed as a chemical pretreatment process to convert the original, high MW polymer to lower MW compounds in an attempt to improve the biotreatability of the waste‐water. The partially oxidized effluents formed during wet oxidation at temperatures up to 403 K were separated by nanofiltration where larger molecules were recycled into the wet oxidation reactor, while the permeate leaving the filtration step was treated biologically. At a biological residence time (τ_B) of 12 h and 3 h, the resulting total organic carbon (TOC) removal in the biological step was as high as 94% and 87%, respectively. Conversely, a continuous aerobic biological process was found inadequate to completely mineralize the original wastewater, since at τ_b of 96 h only about 60% to 70% TOC removal was achieved, while at τ_b of 12 h the original wastewater was practically non‐biockgradable.     

Reconstruction from 2-D wavelet transform modulus maxima usingprojection

Wavelet transform modulus maxima can be used to characterise sharp variations such as edges and contours in an image. The authors analyse the a priori constraints present in the wavelet transform modulus maxima representation. A new projection-based algorithm which enforces all the a prior constraints in the representation is proposed. Quadratic programming is used to obtain a sequence which satisfies the maxima constraint. Thus realising the projection onto the maxima constraint space. To save computation, an approximate method to obtain a sequence which satisfies the maxima constraint is given. The new algorithm is shown to provide better solution than the original reconstruction algorithm of Mallat and Zhong (1992). The authors also propose a simple method to accelerate the algorithm. The acceleration is achieved by the incorporation of a momentum term which exploits the high correlation between the difference images between two consecutive iterations. The simulation results show that the proposed algorithm gives good reconstruction and the simple acceleration method can significantly improve the convergence rate     

Water Productivity in a Rigid Irrigation Delivery System

The rotational irrigation water delivery (warabandi) system practiced in the Indus river basin of Pakistan has continued for 100 years. Irrigation water allocated to the farmers under the warabandi system is proportional to farm size and is fixed. This rigid allocation system has been partly justified by its contribution to social equity though this may have been at the cost of economic gains. In order to assess the operation of warabandi’s basic rules, a farmers’ survey was completed from 124 farmers located on five watercourses. A questionnaire was administered to each farmer and farm management data were gathered. As fresh water resources are under stress and becoming scarce their efficient use in all applications should be assured in water allocations. It is shown from the survey results that water allocation based on very limited criteria does not maximize the socio-economic benefits gained from the use of scarce water. Thus, it is suggested that the existence or non-existence of fresh groundwater resources along with other critical variables should be taken into consideration when making canal water allocation decisions. Missed water deliveries due to failure of the canal system appear to be the largest cause of losses. Water charges need to be increased to fund large improvements in canal maintenance programs. It is pointed out that a framework should be developed as a tool to improve water productivity for Pakistan. This should include: consideration of the gross area of a tertiary canal, sensitivity of crop growth stage to water shortage, crop value, bias of allocation towards most water use efficient areas and water use efficient crops, the potential losses from water deficiency.     

"Age and sex differences in reaction time in adulthood: Results from the United Kingdom Health and Lifestyle Survey": Correction.

Reports an error in "Age and sex differences in reaction time in adulthood: Results from the United Kingdom Health and Lifestyle Survey" by Geoff Der and Ian J. Deary (Psychology and Aging, 2006[Mar], Vol 21[1], 62-73). In the article, the link to supplemental material is incorrect. The correct supplemental link follows. Supplemental materials are available online at http://dx.doi.org/10.1037/0882-7974.21.1.62.supp. (The following abstract of the original article appeared in record 2006-03906-007.) Reaction times (RTs) slow and become more variable with age. Research samples are typically small, biased, and of restricted age range. Consequently, little is known about the precise pattern of change, whereas evidence for sex differences is equivocal. The authors reanalyzed data for 7,130 adult participants in the United Kingdom Health and Lifestyle Survey, originally reported by F. A. Huppert (1987). The authors modeled the age differences in simple and 4-choice reaction time means and variabilities and tested for sex differences. Simple RT shows little slowing until around 50, whereas choice RT slows throughout the adult age range. The aging of choice RT variability is a function of its mean and the error rate. There are significant sex differences, most notably for choice RT variability. (PsycINFO Database Record (c) 2010 APA, all rights reserved)