What risk assessments can tell us about setting criteria

The Food Safety Objective (FSO) paradigm has been developed as a risk-based approach to microbial food safety. To be operational, this paradigm requires that an Acceptable Level of Protection (ALOP) and a FSO be quantitatively defined. It then becomes the industry’s task to produce foods that achieve the FSO. A two-dimensional risk assessment, which separates variation and uncertainty, can help design a process or validate an existing process. If the initially proposed or existing process parameters do not meet the FSO, the sensitivity analysis can show which parameters have high uncertainty or variability that can be better controlled or how much a parameter must change for the process to achieve the FSO.     

Information loss in knowledge compilation: A comparison of Boolean envelopes

Since Selman and Kautz's seminal work on the use of Horn approximation to speed up the querying of knowledge bases, there has been great interest in Boolean approximation for AI applications. There are several Boolean classes with desirable computational properties similar to those of the Horn class. The class of affine Boolean functions, for example, has been proposed as an interesting alternative to Horn for knowledge compilation. To investigate the trade-offs between precision and efficiency in knowledge compilation, we compare, analytically and empirically, four well-known Boolean classes, and their combinations, for ability to preserve information. We note that traditional evaluation which explores unit-clause consequences of random hard 3-CNF formulas does not tell the full story, and we complement that evaluation with experiments based on a variety of assumptions about queries and the underlying knowledge base.     

Achievable performance of dynamic channel assignment schemes undervarying reuse constraints

We introduce a reward paradigm to derive novel bounds for the performance of dynamic channel assignment (DCA) schemes. In the case of uniform reuse, our bounds closely approach the performance of maximum packing (MP), which is an idealized DCA scheme. This suggests not only that the bounds are extremely tight, but also that no DCA scheme, however sophisticated, will be able to achieve significant capacity gains beyond those obtained from MP. Our bounds extend to varying reuse scenarios which may arise in the case of reuse partitioning techniques, measurement-based DCA schemes, or micro-cellular environments. In these cases, the bounds slightly diverge from the performance of MP, which inflicts higher blocking on outer calls than inner calls, but not to the extent required to maximize carried traffic. This reflects the inherent tradeoff that arises in the case of varying reuse between efficiency and fairness. Asymptotic analysis confirms that schemes which minimize blocking intrinsically favor inner calls over outer calls, whereas schemes which do not discriminate among calls inevitably produce higher network-average blocking. Comparisons also indicate that DCA schemes are crucial in fully extracting the potential capacity gains from tighter reuse     

Robert Bruce Ammons (1920-1999): Obituary.

Presents an obituary for Robert Bruce Ammons. Ammons was a researcher, professor, and founder of Perceptual and Motor Skills and Psychological Reports. He dedicated his life to encouraging scientific originality. He was a licensed clinician, a fellow of the American Association for the Advancement of Science, Sigma Xi, and several divisions of the American Psychological Association (Experimental Psychology, Experimental Analysis of Behavior, Clinical Psychology, and History of Psychology), and he was a member of more than 30 national and international professional organizations. He held numerous offices in the Montana Psychological Association from 1958 to 1985, including being the president and secretary of the Montana Psychological Association's Internal Certification Board. His teaching centered on the history of psychology as a modern science, the psychology of the scientist, techniques of research strategy and theory construction, child development, and aesthetics. Ammons passed away in 1999. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of Conjugated Linoleic Acid, Salt, and Sodium Tripolyphosphate on Physical, Sensory, and Instrumental Color Characteristics of Beef Striploins

ABSTRACT:  USDA Select striploins (IMPS 180; n = 24) were cut into thirds (anterior, medial, and posterior) and assigned to 1 of 8 treatments utilizing a randomized incomplete block design. Treatments included (1) control (C); (2) 1.5% conjugated linoleic acid (conjugated linoleic acid = CLA) (CGA); (3) 0.4% sodium tripolyphosphate (PHO); (4) 0.5% salt (SAL); (5) 0.4% sodium tripolyphosphate, 0.5% salt (SPH); (6) 0.4% sodium tripolyphosphate, 1.5% CLA (PCL); (7) 0.5% salt, 1.5% CLA (SCL); and (8) 0.4% sodium tripolyphosphate, 0.5% salt, 1.5% CLA (SPC). Treatments were injected with solutions to 110% (10% pump) of their original weight. Treatments with CLA had higher ( P < 0.05) marbling scores than treatments that did not. Not including SAL, treatments with salt, or phosphate or a combination of the two had higher tenderness values when sampled by panelists. Fresh steaks with inclusion of CLA had greater amounts ( P < 0.05) of the CLA isomers than steaks not having CLA. Cooked steaks having CLA also had greater amounts ( P < 0.05) of CLA, except for SCL, which were not different ( P > 0.05) from the non-CLA treatments. Day was a significant source of variability for a *, b *, and saturation index. Treatment × day interactions were significant ( P < 0.05) for hue angle and L * values. These data suggest that inclusion of CLA can increase amounts of CLA isomers without major deleterious effects to instrumental, physical, and quality characteristics of beef striploin steaks.     

Selectivity enhancement for high-speed GC analysis of volatile organic compounds with portable instruments designed for vacuum-outlet and atmospheric-pressure inlet operation using air as the carrier gas.

A tandem ensemble of two 4.5-m-long x 0.25-mm-i.d. capillary columns with the first using a 0.50-microm film of nonpolar dimethyl polysiloxane and the second using a 0.25-microm film of polar trifluoropropylmethyl polysiloxane is operated with atmospheric pressure air as the carrier gas and an outlet pressure of 50.5 kPa established using a small vacuum pump. A thicker stationary-phase film is used in the first column to increase retention for very volatile compounds. This significantly increases the resolution of these compounds. The thicker film in the first (nonpolar) column decreases the polarity of the tandem column ensemble and, thus, changes its selectivity. A low-dead-volume valve, connected between the column junction point and a source of atmospheric pressure air, is used to obtain pulsed modulation of the carrier gas flow through the column ensemble. When the valve is open, the ensemble inlet pressure and the junction-point pressure are nearly the same, and carrier gas flow nearly stops in the first column, and flow in the second column increases. Enhanced resolution of a component pair that is separated by the first column but coelutes from the column ensemble can be obtained if the valve is opened for a few seconds after one of the components has crossed the junction and is in the second column, but the other component is still in the first column. A sequence of appropriately timed pulses is used to obtain enhanced resolution of several pairs of components that coelute from the column ensemble. These methods enabled the complete separation of an 18-component vapor mixture of common solvents in air in 3.5 min.     

Adult Age Differences in the Implicit and Explicit Components of Top-Down Attentional Guidance During Visual Search.

Two experiments investigated adult age differences in the explicit (knowledge-based) and implicit (repetition priming) components of top-down attentional guidance during discrimination of a target singleton. Experiment 1 demonstrated an additional contribution of explicit top-down attention, relative to the implicit effect of repetition priming, which was similar in magnitude for younger and older adults. Experiment 2 examined repetition priming of target activation and distractor inhibition independently. The additional contribution of explicit top-down attention, relative to the repetition priming of distractor inhibition, was greater for older adults than for younger adults. The results suggest that some forms of top-down attentional control are preserved as a function of adult age and may operate in a compensatory manner. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The excretion mechanism of the spin label proxyl carboxylic acid (PCA) from the rat monitored by X-band ESR and PEDRI

Proton electron double resonance imaging (PEDRI) was used for monitoring in vivo the distribution, metabolism and, in particular, the excretion mechanism of the exogenous nitroxide free radical proxyl carboxylic acid (PCA) in the rat. PCA clearance half-lives through liver, abdominal vessels, and renal tissues were determined from a series of PEDRI images for normal rats (n = 5) and rats treated with probenecid (n = 5), a competitive inhibitor of the tubular secretion process. The approximately doubled renal half-lives of the treated animals suggest that tubular secretion accounts for about 50% of PCA renal loss in the normal rat and reabsorption is insignificant. PCA binding to bovine serum albumin was investigated by X-band ESR and the bound fraction was found to be less than 10% of the total PCA. Most probably, PCA binds to hydrophilic sites. Blood PCA concentration investigated by X-band ESR exhibited biphasic behavior and PEDRI results confirmed the in vivo metabolic reduction of PCA by rat liver cells.