Disaggregating measurement uncertainty from population variability and Bayesian treatment of uncensored results

In making low-level radioactivity measurements of populations, it is commonly observed that a substantial portion of net results is negative. Furthermore, the observed variance of the measurement results arises from a combination of measurement uncertainty and population variability. This paper presents a method for disaggregating measurement uncertainty from population variability to produce a probability density function (PDF) of possibly true results. To do this, simple, justifiable and reasonable assumptions are made about the relationship of the measurements to the measurands (the 'true values'). The measurements are assumed to be unbiased, that is, that their average value is the average of the measurands. Using traditional estimates of each measurement's uncertainty, a likelihood PDF for each individual's measurand is produced. Then using the same assumptions and all the data from the population of individuals, a prior PDF of measurands for the population is produced. The prior PDF is non-negative, and the average is equal to the average of the measurement results for the population. Using Bayes's theorem, posterior PDFs of each individual measurand are calculated. The uncertainty in these bayesian posterior PDFs appears to be all Berkson with no remaining classical component. The method is applied to baseline bioassay data from the Hanford site. The data include (90)Sr urinalysis measurements of 128 people, (137)Cs in vivo measurements of 5337 people and (239)Pu urinalysis measurements of 3270 people. The method produces excellent results for the (90)Sr and (137)Cs measurements, since there are non-zero concentrations of these global fallout radionuclides in people who have not been occupationally exposed. The method does not work for the (239)Pu measurements in non-occupationally exposed people because the population average is essentially zero relative to the sensitivity of the measurement technique. The method is shown to give results similar to classical statistical inference when the measurements have relatively small uncertainty.     

Cyclodextrin-Promoted Fluorescence Detection of Aromatic Toxicants and Toxicant Metabolites in Commercial Milk Products

The detection of polycyclic aromatic hydrocarbons (PAHs) and their metabolites in food and in agricultural sources is an important research objective due to the PAHs’ known persistence, carcinogenicity, and toxicity. PAHs have been found in the milk of lactating cows and in the leaves and stems of plants grown in PAH-contaminated areas, thereby making their way into both cow milk and plant milk alternatives. Reported herein is the rapid, sensitive, and selective detection of 10 PAHs and PAH metabolites in a variety of cow milks and plant milk alternatives using fluorescence energy transfer from the PAH to a high quantum yield fluorophore, combined with subsequent array-based statistical analyses of the fluorescence emission signals. This system operates with high sensitivity (low micromolar detection limits), selectivity (100% differentiation even between structurally similar analytes), and general applicability (for both unmodified lipophilic PAHs and highly polar oxidized PAH metabolites, as well as for different cow and plant milk samples). These promising results show significant potential to be translated into solid-state devices for the rapid, sensitive, and selective detection of PAHs and their metabolites in complex, commercial food products.     

Reduction of titanium dioxide in a nonequilibrium hydrogen plasma

Plasma processing offers improved thermodynamics and kinetics over conventional, thermal processing. In the current work, the reduction of TiO₂ was investigated in a moderate-pressure (p<46 torr) nonequilibrium hydrogen plasma at temperatures below 1273 K; the effect of plasma power, plasma pressure, time, and applied voltage on the extent of the reduction was examined. Reduction of powdered TiO₂ at the surface of a packed bed has produced up to 60 pct conversion of TiO₂ to Ti₂O₃ in only 5 minutes of plasma-specimen contact. While the plasma-assisted reduction occurs at the surface, the reduction of TiO₂ to Ti₅₀O₉₉ within the interior of the bed by diatomic hydrogen establishes a value of that leads to the reoxidation of the Ti₂O₃. The continued reduction of the surface material by monatomic hydrogen from the plasma balances this oxidation process, and a steady-state condition is established. When the interior of the bed is completely reduced to Ti₅₀O₉₉, the partial pressure of water vapor declines, and further reduction of Ti₂O₃ at the surface can proceed. It is hypothesized that the reduction process involves the formation of a Magneli-like oxide between Ti₂O₃ and TiO.     

Evaluation of the antioxidant potential of natural food/plant extracts as compared with synthetic antioxidants and vitamin E in raw and cooked pork patties

Antioxidant potential for previously identified optimum levels of aloe vera (AV), fenugreek (FGK), ginseng (G), mustard (M), rosemary (R), sage (S), soya protein (SPI), tea catechins (TC) and whey protein concentrate (WPC) were evaluated in raw and cooked patties manufactured from frozen pork. The optimum levels determined were: AV (0.25%), FGK (0.01%), G (0.25%), M (0.10%), R (0.10%), S (0.05%), SPI (0.10%), TC (0.25%) and WPC (4%). Test ingredients were evaluated against synthetic antioxidants butylated hydroxyanisole/butylated hydroxytoluene (BHA/BHT) (0.01%) and a supplemented meat containing natural antioxidant, α-tocopherol (1000 mg α-tocopheryl acetate/kg feed). Ranking the decreasing antioxidant effectiveness of added ingredients in raw patties on day 9 showed that: Control>G>SPI>FGK>AV>M>WPC>S>α-tocopherol>R>TC>BHA/BHT. Cooking resulted in a four-fold increase in TBARS values over raw patties with TC being the most effective antioxidant having significantly (P<0.001) lower TBARS values than the cooked control on days 3, 6 and 9. Ranking of decreasing antioxidant effectiveness of added ingredients showed that: M>SPI>G>FGK>α-tocopherol>AV>control>S>BHA/BHT>R>WPC>TC. BHA/BHT had the most beneficial effect on cooked meat redness with Hunter 'a' values being significantly (P<0.05) higher than the control on days 3, 6 and 9. Ranking of Hunter 'a' values for added test ingredients showed that FGK>WPC>control>R>BHA/BHT>α-tocopherol>TC>AV>SPI>M>G>S on day 9. Hunter 'L' and 'b' values showed no significant trend over the storage period in either raw or cooked patties. The pH values of both raw and cooked pork control patties and products containing added test antioxidants were variable and while a number of trends were observed, no significant differences were recorded between samples.     

Leader election using loneliness detection

We consider the problem of leader election (LE) in single-hop radio networks with synchronized time slots for transmitting and receiving messages. We assume that the actual number n of processes is unknown, while the size u of the ID space is known, but is possibly much larger. We consider two types of collision detection: strong (SCD), whereby all processes detect collisions, and weak (WCD), whereby only non-transmitting processes detect collisions. We introduce loneliness detection (LD) as a key subproblem for solving LE in WCD systems. LD informs all processes whether the system contains exactly one process or more than one. We show that LD captures the difference in power between SCD and WCD, by providing an implementation of SCD over WCD and LD. We present two algorithms that solve deterministic and probabilistic LD in WCD systems with time costs of ${\mathcal{O}(\log \frac{u}{n})}$ and ${\mathcal{O}(\min( \log \frac{u}{n}, \frac{\log (1/\epsilon)}{n}))}$ , respectively, where ${\epsilon}$ is the error probability. We also provide matching lower bounds. Assuming LD is solved, we show that SCD systems can be emulated in WCD systems with factor-2 overhead in time. We present two algorithms that solve deterministic and probabilistic LE in SCD systems with time costs of ${\mathcal{O}(\log u)}$ and ${\mathcal{O}(\min ( \log u, \log \log n + \log (\frac{1}{\epsilon})))}$ , respectively, where ${\epsilon}$ is the error probability. We provide matching lower bounds.     

The application of a system-based risk management framework and social network analysis to the Maritime Autonomous Surface Ship system: Who are the decision-makers in the wider system?

Maritime Autonomous Surface Ships (MASS) currently have no formal regulations developed specifically for their operation, as their regulatory framework is still under development. Rasmussen's Risk Management Framework has been used to develop an actor map of the current MASS system in the UK, to show who the actors, decision-makers, and planners are within the wider sociotechnical system and the level at which they sit. From the actor map, two social networks were created, one to show the connections that currently exist between the actors within the MASS system and another to show what a future MASS system could look like if regulations and standards were put in place for MASS. Social Network Analysis was then used to investigate the wider MASS system's dynamics, to understand which actors currently have a high degree of influence within the UK MASS system, and where the shortfalls are in the current MASS system. The analysis showed that the industry and end user levels lacked support from the higher system levels, and the addition of formal regulations and standards in the future MASS system would increase the MASS system's resilience. System recommendations for each level in the Risk Management Framework were then made to suggest ways to increase the influence of the regulators and promote the safe operation of MASS.     

Testicular volume of boys after inguinal herniotomy: combined clinical and radiological follow-up

Many nurse managers practice enterprise-wide resource management across networked departments and facilities. Here's help in understanding how automation can ease the process.     

The influence of a steel rear barrier on the detonation response of a steel covered explosive struck by a steel projectile

Experiments by Weickert showed that the critical impact velocity of a shaped charge jet, required to cause detonation of a steel/explosive/steel laminate, reduced when the explosive thickness reduced. This paper examines the cause of this change using hydrocode simulations with and without a temperature based burn model. The simulations show that the change in critical impact velocity is caused by the reflected shock from the rear plate exceeding the shock at the cover plate. At this point the site of the detonation moves from the cover plate to the rear plate. Further reduction in explosive thickness causes further reduction in critical impact velocity due to the reduced dissipation of the shock reaching the back plate. The change in critical velocity for hemispherical-nosed projectiles is predicted to be not as sharply defined as for flat-nosed projectiles. This is due to a later, third stage reflection from the bulge of the advancing cover plate.