Different rule systems for counting behavior acquired in meaningful and rote contexts of learning.

In a series of 3 experiments, 68 undergraduates learned to a criterion of 2 errorless trials to recite the 1st 12 or 18 responses in a pattern based on Base 3. In Exp I, the pattern was presented as letters (w, d, r, dw, dd,?.?.?.) or as numerals (0, 1, 2, 10, 11,?.?.?.). In Exps II and III, the pattern was presented as letters, and Ss were given a letter-to-digit conversion list (w?=?0, d?=?1, r?=?2) either before or after learning. On a posttest, Ss who knew that the pattern related to numerals during learning performed better on transfer tasks such as addition or further counting in Base 3. Results suggest that different rule systems were acquired even though the same levels of performance on the behavioral objective were achieved. (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A construction of one-point bases in extended lambda calculi

We present a general schema for constructing infinitely-many one-point bases for -calculi extended by finitely-many constants. The constants are usually present in programming languages, and may involve reduction rules other than β-reduction. The construction can be implemented in a functional subset of LISP/Scheme, giving one-point bases for applicative-order calculi extended by constants from the underlying programming language.     

Reactive transport modeling of column experiments for the remediation of acid mine drainage

Reactive transport modeling was used to evaluate the performance of two similar column experiments. The experiments were designed to simulate the treatment of acid mine drainage through microbially mediated sulfate reduction and subsequent sulfide mineral precipitation by means of an organic carbon permeable reactive barrier. Principal reactions considered in the simulations include microbially mediated reduction of sulfate by organic matter, mineral dissolution/precipitation reactions, and aqueous complexation/hydrolysis reactions. Simulations of column 1, which contained composted leaf mulch, wood chips, sawdust, and sewage sludge as an organic carbon source, accurately predicted sulfate concentrations in the column effluent throughout the duration of the experiment using a single fixed rate constant for sulfate reduction of 6.9 x 10(-9) mol L(-1) s(-1). Using the same reduction rate for column 2, which contained only composted leaf mulch and sawdust as an organic carbon source, sulfate concentrations at the column outlet were overpredicted at late times, suggesting that sulfate reduction rates increased over the duration of the column experiment and that microbial growth kinetics may have played an important role. These modeling results suggest that the reactivity of the organic carbon treatment material with respect to sulfate reduction does not significantly decrease over the duration of the 14-month experiments. The ability of the columns to remove ferrous iron appears to be strongly influenced by the precipitation of siderite, which is enhanced by the dissolution of calcite. The simulations indicate that while calcite was available in the column, up to 0.02 mol L(-1) of ferrous iron was removed from solution as siderite and mackinawite. Later in the experiments after approximately 300 d, when calcite was depleted from the columns, mackinawite became the predominant iron sink. The ability of the column to remove ferrous iron as mackinawite was estimated to be approximately 0.005 mol L(-1) for column 1. As the precipitation of mackinawite is sulfide limited at later times, the amount of iron removed will ultimately depend on the reactivity of the organic mixture and the amount of sulfate reduced.     

Dose equivalent measurements in a strongly pulsed high-energy radiation field

The stray radiation field outside the shielding of high-energy accelerators comprises neutrons, photons and charged particles with a wide range of energies. Often, accelerators operate by accelerating and ejecting short pulses of particles, creating an analogue, pulsed radiation field. The pulses can be as short as 10 micros with high instantaneous fluence rates and dose rates. Measurements of average dose equivalent (rate) for radiation protection purposes in these fields present a challenge for instrumentation. The performance of three instruments (i.e. a recombination chamber, the Sievert Instrument and a HANDI-TEPC) measuring total dose equivalent is compared in a high-energy reference radiation field (CERF) and a strongly pulsed, high-energy radiation field at the CERN proton synchrotron (PS).     

RFI Suppression Components: State of the Art; New Developments

This paper reviews passive and active building elements for RFI suppression: inductors, capacitors, frequency-sensitive and voltagesensitive resistors, and their interconnections to form multipole structures, of lumped and distributed types. After presentation of the state of the art, rules are given for the design of good RFI components. Trends are shown in new developments, especially the new technologies of manufacturing special dielectric and magnetic media. The possibility is discussed of generalizing the concept of "damping" as compared to pure reactive "filtering." Some recent research and development results are presented concerning components spreading RFI suppression along distributed structures, the important role of partition, and finally, integrated "dielectromagnetic" structures.     

Can you repeat that? Qualitative effects of repetition and advance organizers on learning from science prose.

88 female college students who did not have strong backgrounds in natural science listened to a short passage about radar or Ohm's law either 1, 2, or 3 times. Overall amount recalled increased with number of presentations, but there was a pattern in which recall of conceptual principles and related information increased sharply with repetition, whereas recall of formal equations and concrete analogies did not. In addition, problem-solving performance increased with number of repetitions, but verbatim recognition declined. Advance organizers presented before a single presentation tended to produce recall and problem-solving performance most similar to that obtained with repeated presentations. Results suggest that Ss tend to use qualitatively different reading strategies on the 1st presentation of science prose than on the 3rd presentation. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Principles and applications of ion beam techniques for the analysis of solids and thin films

This paper reviews in principle and by examples how a collimated mono-energetic and mono-atomic beam incident on a target provides information on its structure and composition when the energy of the back-scattered beam atoms, or of the particles generated by nuclear reactions, is analyzed. Examples are selected with particular emphasis on thin films and Si technology. For convenience, we define three different energy ranges of the incident beam (low energies from 1 to 6 keV, medium energies from 100 to 500 keV and high energies from 1 to 2 MeV) and discuss each range separately, according to the following table of contents.     

Modeling kinetic processes controlling hydrogen and acetate concentrations in an aquifer-derived microcosm

Groundwater contaminants may degrade via fermentation to intermediate species, which are subsequently consumed by terminal electron-accepting processes (TEAPs). A numerical model of an aquifer-derived laboratory microcosm is developed to simulate the dynamic behavior of fermentation and respiration in groundwater by coupling microbial growth and substrate utilization kinetics with a formulation that also includes aqueous speciation and other geochemical reactions including surface complexation, mineral dissolution, and precipitation. The model is used to test approaches that currently make use of H2(aq) to diagnose prevalent TEAPs in groundwater. Competition between TEAPs is integral to the conceptual model of the simulation, and the results indicate that competitive exclusion is significant but with some overlap found in the temporal sequence of TEAPs. Steady-state H2(aq) concentrations observed during different TEAPs do not differ significantly. The results are not consistent with previous applications of the partial equilibrium approach since most TEAP redox pairs exhibit free energies that suggest a particular process is able to proceed, yet observations here show that this process does not proceed.     

Structural organization of the intact bacterial cellulosome as revealed by electron microscopy

The architecture of the intact cellulosome of Clostridium thermocellum, a huge extracellular multi-polypetide bacterial enzyme complex engaged in degradation of cellulose, was investigated by electron microscopy. This was done because former electron microscopic studies aimed at elucidation of the structure of polycellulosomes and cellulosomes were restricted by the fact that data on macromolecular details could only be derived from deformed or disrupted enzyme complexes, or by application of cryo preparation and imaging techniques yielding insufficient resolution. The shape of well-preserved cellulosomes was more or less spherical, often similar to that of an olive fruit with a cavity. Therein, multiple fibrillar structures could be visualized, interpreted to be the proximal stretches of copies of the fibrillar protein Cip A ('scaffoldin'), the nonenzymatic scaffolding protein known to function as attachment site for the enzymatic subunits, as well as fibrillar parts of anchoring proteins. The enzymatic subunits were depicted to be attached, in a repetitive fashion, to the distal stretches of the Cip A proteins. The enzymatic subunits were seen, in the intact cellulosome, to form a shell-like complex substructure surrounding the cavity. Obviously, this kind of architecture makes sure that the catalytic domains of the enzymatic subunits are exposed to the environment, and, hence, to the substrate, the cellulose fibrils. Attempts were made to demonstrate the alternating occurrence of coiled domains and fibrillar stretches along the elongated protein Cip A previously characterized by sequencing, X-ray, and NMR studies. To this end, Cip A molecules, with adhering enzymatic subunits, were partially removed from their native location within the cellulosome, "stretched" by hydromechanical forces directly on the electron microscopic support film, negatively stained, and depicted by electron microscopy. The alternating occurrence of presumed coiled domains and fibrillar stretches along Cip A could be visualized, together with detached enzymatic subunits found on the support film.