Dominic I: Progress toward domain independence in design by iterative redesign

This paper describes the first working version of a program called Dominic that performs design by iterative redesign in a domain-independent manner. The paper describes in detail the program's strategy, which stresses the concept of redesign dependencies to guide its redesign process. Dominic has been successfully tested in four different domains. Its performance on two of these (v-belt drive design and design of extruded heat sinks) is presented here. The redesign class of design problems on which Dominic works is that large class of problems that are intellectually manageable and solvable without subdivision into smaller parts. This includes the various subproblems ultimately created when large complex problems are decomposed for solution. Dominic is a hill-climbing algorithm, similar in this respect to standard optimization methods. However, its problem formulation or input language is more flexible for some design applications than optimization techniques. Work is continuing on a Dominic II in an effort to overcome some of the limitations of Dominic.     

Development of a simple model device for in vitro gastric digestion investigation

There have been some reports in the literature of model gastric digestion systems to mimic the dynamic physiological processes within the gastrointestinal tract. However, such devices often require the specification of many control parameters making routine digestion tests unfeasible. This paper introduces a simple in vitro digestion device, comprising of a water-jacketed glass vessel into which a spherical Teflon probe of variable diameter can be inserted. The probe is controlled by a texture analyser to simulate the kinetics of a food digestion process. Using this device under well controlled hydrodynamic flow and biochemical conditions key digestion parameters such as pH, food particle size, protein release, lipid release, cloudiness, etc, can be determined. Feasibility tests of the model device have been conducted using roasted and non-roasted peanuts particles. The status of peanut digestion was examined by the changes in particle size distribution and the mean particle size. Significant differences of surface microstructure have also been observed for peanut particles after the digestion. The influence of parameters such as food to gastric juice ratio, the probe speed and pepsin concentration have been examined in this work. Initial results confirm that all these factors influence the kinetic process of gastric digestion considerably and should be well regulated in any in vitro digestion investigations. We propose that the model device has the advantages of easy control and operation and furthermore could be an ideal tool for routine in vitro gastric digestion studies.     

Effect of enhancement on the formation of heterocyclic amines in cooked pork loins: Preliminary studies

Heterocyclic amines (HCAs) which are produced in meats cooked at high temperature a risk factor for certain human cancers. This study evaluated the effect of enhancement on HCA formation in cooked pork loins. Three samples of pork loin were prepared including non-injected loin, 12% water-injected loin, and 12% salt/phosphate injected loin. The HCAs were identified in all samples: PhIP (2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine), MeIQx (2-amino-3,8-dimethylimidazo [4,5-f]quinoxaline), and DiMeIQx (2-amino-3,4,8-trimethylimidazo [4,5-f]quinoxaline). Injection of salt/phosphate significantly reduced the level of PhIP by 42.7%, MeIQx by 79.0%, and DiMeIQx by 75.0%. Enhancement with water alone did not reduce HCA formation.     

TESTING FOR GAUSSIANITY AND LINEARITY OF A STATIONARY TIME SERIES

Abstract. Stable autoregressive (AR) and autoregressive moving average (ARMA) processes belong to the class of stationary linear time series. A linear time series { } is Gaussian if the distribution of the independent innovations {ε( t )} is normal. Assuming that E ε( t ) = 0, some of the third-order cumulants c_xxx= Ex ( t ) x ( t + m ) x ( t + n ) will be non-zero if the ε( t ) are not normal and E ε³( t )≠O. If the relationship between { x ( t )} and {ε( t )} is non-linear, then { x ( t )} is non-Gaussian even if the ε( t ) are normal. This paper presents a simple estimator of the bispectrum, the Fourier transform of { c _xxx( m, n )}. This sample bispectrum is used to construct a statistic to test whether the bispectrum of { x ( t )} is non-zero. A rejection of the null hypothesis implies a rejection of the hypothesis that { x ( t )} is Gaussian. Another test statistic is presented for testing the hypothesis that { x ( t )} is linear. The asymptotic properties of the sample bispectrum are incorporated in these test statistics. The tests are consistent as the sample size N →-∞     

Poor performance following unsolvable problems: Learned helplessness or egotism?

People often perform poorly on tasks following experience with unsolvable problems. The current experiment tested 2 competing explanations (learned helplessness and egotism) for this performance deficit. 40 college students were given either solvable or unsolvable discrimination problems and then a series of anagrams that were alleged to be either highly or moderately difficult. Ss previously given unsolvable problems did better on the anagrams when led to believe that the anagrams were highly difficult than when led to believe that the anagrams were moderately difficult. This result is contrary to a learned helplessness theory interpretation, which attributes performance deficits following unsolvable problems to the belief that outcomes are independent of responses. Instead, this result supports an egotism explanation, which maintains that people are not likely to try hard on a task following experience with unsolvable problems (i.e., following failure), unless a poor performance would not pose a further threat to their self-esteem. (27 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Leak detection in polyethylene terephthalate bottles filled with water and pulped and unpulped orange juice using a vacuum decay system

This research evaluated an offline vacuum decay leak detection system for 1775-ml polyethylene terephthalate (PET) bottles. These bottles were filled with water and pulped and unpulped orange juice and induction sealed with an aluminum liner and an outer 38-mm continuous thread polypropylene cap. The objectives of this study were to evaluate (i) minimum leak size sensitivity of the instrument; (ii) ability to identify weak but nonleaking seals; (iii) effect of varying fill heights on the equipment's sensitivity; and (iv) percentage of false-positive and negative results likely to be obtained during a normal test run. To meet these objectives, leaks 5, 10, 15, 20, 30, 40, and 50 microm were created in the PET bottles. A second set of bottles was induction sealed at high voltage and 1, 1.5, 2, 2.5, 3, 3.5, and 4 s of dwell time. A third set of bottles with good seals was filled with differing headspace measurements of brimful, 1, 2, 3, 4, and 5 cm. After optimizing the equipment, leak tests on random sets of leaking and nonleaking bottles showed 0.0% false-positive and 0.0% negative identifications. Results showed 5-microm minimum leak size detection for bottles filled with all products. Optimum seal conditions were >2 but <3 s at high voltage. Product fill heights >2 to < or =3 cm did not affect the efficiency of the equipment. These results show that this vacuum decay system has potential for use in identifying leaks in PET bottles used for food packaging.     

The relationship of dietary fats to prostaglandin biosynthesis

The direct and indirect evidence that the fatty acid composition of dietary fat is involved in the regulation of prostaglandin biosynthesis was reviewed. Direct evidence included effects of essential fatty acid deficiencies and excesses on endogenous tissue levels and production rates of prostaglandins by several tissues. Indirect evidence included lipolytic, platelet aggregatory, hypertensive, inflammatory and immune responses. In general, composition of dietary fat did not affect prostaglandin biosynthesis unless a biochemical essential fatty acid deficiency was induced or the linoleate to saturated fatty acids ratio of the dietary fat was greater than 5. Most results were interpreted in light of changing fatty acid composition; however, very few direct measurements have been made.