Furans and other volatile compounds in ground roasted and espresso coffee using headspace solid-phase microextraction: Effect of roasting speed

The profile of major classes of furanic compounds, as well as other volatile compounds, was evaluated by headspace solid-phase microextraction GC/MS in Arabica ground coffee roasted at three speeds, and in their respective espresso coffees. A total of 113 and 105 volatile compounds were respectively identified in ground coffee and espresso coffee. They were clustered in the following chemical classes: furans, pyrroles, pyridines, pyrazines, ketones, hydrocarbons, aldehydes and others. Results from Principal Component Analysis (PCA) using the data of major volatile class as variables showed that the levels (expressed as relative percentage of total peak area) of furans and pyrroles were higher in espresso samples, whereas those of pyrazines and ketones were higher in ground samples. Slow roasting speed favoured pyridines formation, while medium and fast roasting speed favoured ketones formation. The most representative furanic compound in ground samples was furfuryl alcohol, followed by furfuryl acetate, 2-furfural, 2-methylfuran and 5-methylfurfural. In espresso samples, the levels of 2-methylfuran, 2-furfural, furfuryl formate, 5-methylfurfural and furfuryl acetate were largely increased while the proportion of furfuryl alcohol was strongly reduced in comparison to ground coffee. High roast speed increased formation of 2-furfural and 5-methyl furfural in espresso coffee.     

Adoption of New Irrigation Technology Under Production Risk

This paper investigates the factors affecting adoption of new irrigation technologies and also addresses the linkage between this type of technology and production risk. The risk-premium associated with the use of water is estimated by adapting a moment-based approach. Farm-level data were collected from a sample of 187 wheat farms, located in the three major districts of Fars province of Iran during the years 2002 and 2003. Results of this study demonstrate that the risk premium decrease with new irrigation technology. Also, it is concluded that the farmer-specific relative risk premium has positive and significant effect on the decision to adopt the new irrigation technologies. So, farmers that are more risk-averse with respect to their use of water are more likely to adopt new irrigation technologies that allow them to save water and decrease their production (yield) risk.     

Effect of Particle Additions on Drying Stresses and the Green Density of Sol-Gel-Processed Three-Dimensional Ceramic-Matrix Composites

This paper investigates sol-gel processing of three-dimensional (3-D) ceramic-matrix composites, focusing on the effect of addition of particles on drying stresses and composite green density. A 3-D woven carbon fiber/silica composite was used as the model material system for the investigation. Composites were fabricated with silica particle additions to the silica sol using a pressure infiltration technique, and the drying rate and matrix cracking were characterized. The particle size was varied in order to study the role of particle additions in the processing. Ammonium hydroxide (NH₄OH) and a particle coating agent, 3-(trimethoxysilyl)propyl methacrylate (TPM), were added in the mixture of particles and sol to improve particle packing in the preform. Sol-gel processing with the addition of particles proves to be an effective route to fabricate 3-D ceramic-matrix composites with higher green density and less matrix cracking.     

Ancient and New Algorithms for Load Balancing in the l p Norm

We consider the on-line load balancing problem where there are m identical machines (servers) and a sequence of jobs. The jobs arrive one by one and should be assigned to one of the machines in an on-line fashion. The goal is to minimize the sum (over all machines) of the squares of the loads, instead of the traditional maximum load. We show that for the sum of the squares the greedy algorithm performs within 4/3 of the optimum, and no on-line algorithm achieves a better competitive ratio. Interestingly, we show that the performance of Greedy is not monotone in the number of machines. More specifically, the competitive ratio is 4/3 for any number of machines divisible by 3 but strictly less than 4/3 in all the other cases (although it approaches 4/3 for a large number of machines). To prove that Greedy is optimal, we show a lower bound of 4/3 for any algorithm for three machines. Surprisingly, we provide a new on-line algorithm that performs within 4/3 -δ of the optimum, for some fixed δ>0 , for any sufficiently large number of machines. This implies that the asymptotic competitive ratio of our new algorithm is strictly better than the competitive ratio of any possible on-line algorithm. Such phenomena is not known to occur for the classic maximum load problem. Minimizing the sum of the squares is equivalent to minimizing the load vector with respect to the l ₂ norm. We extend our techniques and analyze the exact competitive ratio of Greedy with respect to the l _p norm. This ratio turns out to be 2 - Θ(( ln p)/p) . We show that Greedy is optimal for two machines but design an algorithm whose asymptotic competitive ratio is better than the ratio of Greedy. Received January 2, 1998; revised December 12, 1998.     

Optimization of alkylresorcinols extraction from triticale bran using response surface methodology

Optimization conditions for alkylresorcinols (ARs) extraction from triticale bran were determined using response surface methodology. A central composite design was used to determine the effects of extraction temperature (degrees Celsius) and solid-to-solvent ratio (weight per volume) on yield of saturated, unsaturated and total ARs. Extraction of ARs was affected significantly (p value????0.05) by temperature and solid-to-solvent ratio on the yield of saturated, unsaturated and total ARs. The highest quantity of total ARs from triticale bran was extracted at 24?°C between 16 and 24?h at a solid-to-solvent ratio (weight per volume) of 1:40 and ranged from 278 to 308?mg/100?g, while saturated and unsaturated ARs were 163 to 225?mg/100?g and 22 to 29?mg/100?g, respectively. The ARs identified by high-performance liquid chromatography included: C15:0, C17:0, C19:0, C21:0, C23:0 and C25:0. Also some unsaturated analogues (12.4% to 14.0%) were found including C17:1, C19:1, C21:1 and C23:1. Analysis of variance (p value?=?0.05) indicated that the response surface methodology (RSM) developed for saturated, unsaturated and total ARs were adequate and explained most of the variability (85% to 89%) with high coefficient of multiple determination (R ²?=?0.89). The main effect of the response variable was quadratic rather than a linear function. Our results showed that RSM is a tool that is useful to optimise experimental conditions for the extraction of ARs.     

Computer-based learning of neuroanatomy: A longitudinal study of learning, transfer, and retention.

A longitudinal experiment was conducted to evaluate the effectiveness of new methods for learning neuroanatomy with computer-based instruction. Using a three-dimensional graphical model of the human brain and sections derived from the model, tools for exploring neuroanatomy were developed to encourage adaptive exploration. This is an instructional method that incorporates graphical exploration in the context of repeated testing and feedback. With this approach, 72 participants learned either sectional anatomy alone or whole anatomy followed by sectional anatomy. Sectional anatomy was explored either with perceptually continuous navigation through the sections or with discrete navigation (as in the use of an anatomical atlas). Learning was measured longitudinally to a high performance criterion. Subsequent tests examined transfer of learning to the interpretation of biomedical images and long-term retention. There were several clear results of this study. On initial exposure to neuroanatomy, whole anatomy was learned more efficiently than sectional anatomy. After whole anatomy was mastered, learners demonstrated high levels of transfer of learning to sectional anatomy and from sectional anatomy to the interpretation of complex biomedical images. Learning whole anatomy prior to learning sectional anatomy led to substantially fewer errors overall than learning sectional anatomy alone. Use of continuous or discrete navigation through sectional anatomy made little difference to measured outcomes. Efficient learning, good long-term retention, and successful transfer to the interpretation of biomedical images indicated that computer-based learning using adaptive exploration can be a valuable tool in instruction of neuroanatomy and similar disciplines. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Discussing smart pills versus endorsing smart pills: Reply to Swanson, Wigal, and Volkow (2011) and Elliott and Elliott (2011).

We find much of interest, and little to disagree with, in the commentaries on our article. We take issue only with the suggestion that our article was provocative and submit that the attempt to understand the use of stimulants as smart pills does not imply an endorsement of the practice. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

On-Line Competitive Algorithms for Call Admission in Optical Networks

We study the on-line call admission problem in optical networks. We present a general technique that allows us to reduce the problem of call admission and wavelength selection to the call admission problem. We then give randomized algorithms with logarithmic competitive ratios for specific topologies in switchless and reconfigurable optical networks. We conclude by considering full duplex communications. Received August 16, 1997; revised May 11, 1998.     

Major oil exporters may profit rather than lose, in a carbon-constrained world

The Organization of Petroleum Exporting Countries (OPEC) claims compensation for losses in expected oil export revenues due to CO₂ mitigation measures in developing countries. These losses are expected for two primary reasons: a reduction in the consumption of oil in importing countries and a reduction in the producer price of oil (taxation in an importing country implies a transfer of rents from producers to consumers). So far, most studies have focused on these two mechanisms and corroborated that revenue losses for OPEC are to be expected. However, there are also mechanisms that may be expected to raise the price of oil products. In a cost-effective regime for dealing with climate change, i.e., a regime in which all or most countries participate and in which the same carbon price is applied on all carbon-emitting activities, the cost of using unconventional oil, or synthetic diesel from coal, will increase even more than the cost of using conventional oil. Given that reserves of conventional oil are expected to dwindle over time, heavy oils and coal to liquids might set the long-run price for liquid fuels, which means that the price of oil would increase beyond the carbon fee; i.e., the rent on conventional oil would increase. We use an energy-economic optimization model to analyze these three mechanisms. We find that the net present value of OPEC revenue from conventional oil increases slightly (at most by 4 percent) with a global CO₂ restriction regime. We also consider conditions under which this result does not hold.     

Characterization of Polyphasic Silicon Carbide Using Surface-Enhanced Raman and Nuclear Magnetic Resonance Spectroscopy

The present report explores the use of cross-polarization (CP) and single-pulse magic angle spinning nuclear magnetic resonance (MAS-NMR) as well as normal and surfaceenhanced Raman spectroscopy (SERS), in concert, for characterizing highly crystalline polymorphic silicon carbide ceramics. The combined use of these techniques provides a wealth of information regarding bulk, near-surface, and surface speciation. Both Raman and SERS are promising techniques for fracture surface characterization of these systems. The application of CPMAS-NMR and SERS to the study of ceramics is reported for the first time in this investigation.