Leveraging machine-learned detectors of systematic inquiry behavior to estimate and predict transfer of inquiry skill

We present work toward automatically assessing and estimating science inquiry skills as middle school students engage in inquiry within a physical science microworld. Towards accomplishing this goal, we generated machine-learned models that can detect when students test their articulated hypotheses, design controlled experiments, and engage in planning behaviors using two inquiry support tools. Models were trained using labels generated through a new method of manually hand-coding log files, “text replay tagging”. This approach led to detectors that can automatically and accurately identify these inquiry skills under student-level cross-validation. The resulting detectors can be applied at run-time to drive scaffolding intervention. They can also be leveraged to automatically score all practice attempts, rather than hand-classifying them, and build models of latent skill proficiency. As part of this work, we also compared two approaches for doing so, Bayesian Knowledge-Tracing and an averaging approach that assumes static inquiry skill level. These approaches were compared on their efficacy at predicting skill before a student engages in an inquiry activity, predicting performance on a paper-style multiple choice test of inquiry, and predicting performance on a transfer task requiring data collection skills. Overall, we found that both approaches were effective at estimating student skills within the environment. Additionally, the models’ skill estimates were significant predictors of the two types of inquiry transfer tests.     

Structural analysis of the intervertebral discs adjacent to an interbody fusion using multibody dynamics and finite element cosimulation

This work describes a methodology for the dynamic and structural analysis of complex (bio)mechanical systems that joins both multibody dynamics and finite element domains, in a synergetic way, through a cosimulation procedure that takes benefit of the advantages of each numerical formulation. To accomplish this goal, a cosimulation module is developed based on the gluing algorithm X-X, which is the key element responsible for the management of the information flux between the two software packages (each using its own mathematical formulation and code). The X-X algorithm uses for each cosimulated structure multiple pairs of reference points whose kinematics are solved by the multibody module and prescribed, as initial data, to the finite element counterpart. The finite element module, by its turn, solves the structural problem imposed by the prescribed kinematics, calculates the resulting generalized loads applied over the reference points and return these loads back to the multibody module that uses them to solve the dynamic problem and to calculate new reference kinematics to prescribe to the finite element module in the next time step. The proposed method is applied to study the cervical spine dynamics in a pathologic situation in which an intersomatic fusion is simulated to confirm its potential advantages. Taking into account the proposed simulation scenario, a cervical spine multibody model that includes the rigid vertebrae, the facet joints’ and spinous processes’ contacts, ligaments and the finite element models of the intervertebral discs, and their surrogates is developed. The proposed model is simulated for extension in a forward dynamics perspective.     

Modeling and testing of high frequency GPR data for evaluation of structural deformation

The paper describes the application, on a hollow pier, of a high frequency multi-component 2 GHz GPR antenna for the evaluation of deformation induced by mechanical stress. The study, performed in the laboratory, was made on a reinforced concrete hollow pier built to scale 1:5. The GPR survey data were obtained before and after the mechanical stress application, in reflection and transillumination modes. The data interpretation was supported by a GPR theoretical model of a pier. The interpretation of the GPR reflection data was very challenging as the iron rods used to reinforce the pier led to wave diffraction and the air inter-space inside the pier itself produced multiple reflections. No continuous fractures were revealed, probably because the stress caused only micro-fractures. This assumption was supported by analyses of the time slices from reflection data and the first direct wave arrival times from transillumination data. In the second survey we observed increased reflectivity in the time slices and decreased first arrival times of the direct wave, with respect to the first survey. The theoretical GPR data carried out on the physical model, which reproduced the actual pier, were found to be very useful tools for interpreting the actual data as they allow signal to noise separation.     

Evaluation of antioxidant properties of a phosphorated cardanol compound on mineral oils (NH10 and NH20)

Studies on thermal-oxidative stability of a phosphorated antioxidant, synthesized from a natural and renewable resource cashew nut shell liquid (CNSL) was investigated, using a classical thermoanalytical method-thermogravimetric (TG/DTG) in air atmosphere. Its use as an antioxidant agent on the mineral oils NH10 and NH20 was evaluated in comparative studied with a commercial product (diphenyl phosphate - Aldrich). The addition of 1.2-2.0 wt% of phosphorated cardanol compound to the mineral oils has improved their thermal-oxidative stability on 14-18 °C, respectively. The occurrence of major thermal degradation events at higher temperatures (T_max) on additivated oils is an excellent indication of the phosphorated cardanol compound antioxidant properties.     

Squaring architecture for GF(2m) and its applications incryptographic systems

A squaring architecture for standard basis field representation is presented. The architecture is based on the observation that a squaring operation in GF(2^m) can be transformed into an addition and a multiplication of two elements of special form, the computational time of which depends on the form of the field polynomial     

Electrospun nanocomposites from polystyrene loaded with cellulose nanowhiskers

Composite microfibers from polystyrene and cellulose nanowhiskers were produced by electrospinning. The morphology of the microfibers was examined by using scanning and transmission electron microscopies. Surface porosity, unique ribbon‐shapes, and the presence of twists along the fiber axis were observed in the composite microfibers. Thermomechanical properties of processed nanocomposites were studied by differential scanning calorimetry and dynamical mechanical analyses. The reinforcing effect of cellulose nanowhiskers was confirmed as the glassy modulus of electrospun microfibers increased with nanowhisker load. This effect is explained to be the result of mechanical percolation of cellulose nanowhiskers forming a stiff and continuous network held by hydrogen bonding. It is demonstrated that cellulose nanoparticles can be used effectively to reinforce hydrophobic matrices and to produce unique structural properties, enabling new functionalities and properties. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

BATCH VIBRATING FLUID BED DRYER FOR SAWDUST PARTICLES: EXPERIMENTAL RESULTS

In a batch experimental equipment, the behavior of a sawdust dryer in a vibrating fluidized bed is analyzed. Empirical data concerning fluidization velocities, pressure drops and drying kinetics was obtained, and advantages of using vibration in the drying chamber, relative to a conventional fluidized bed, are shown. This technique is presented as an alternative to solve problems of solid agglomeration and bed defluidization. Results show that it is possible to dry sawdust with more than 2 kg/kg moisture, in a vibrating bed keeping a high degree of bed homogeneity and high quality of fluidized state.     

Clonal diversity of Chilean isolates of enterohemorrhagic Escherichia coli from patients with hemolytic-uremic syndrome, asymptomatic subjects, animal reservoirs, and food products

To determine clonal relationship among Chilean enterohemorrhagic Escherichia coli (EHEC) strains from different sources (clinical infections, animal reservoirs, and food), 54 EHEC isolates (44 of E. coli O157, 5 of E. coli O111, and 5 of E. coli O26) were characterized for virulence genes by colony blot hybridization and by pulsed-field gel electrophoresis (PFGE). By colony blotting, 12 different genotypes were identified among the 44 E. coli O157 isolates analyzed, of which the genetic profile stx1+ stx2+ hly+ eae+ was the most prevalent. All human O157 strains that were associated with sporadic cases of hemolytic-uremic syndrome (HUS) carried both the stx1 and stx2 toxin-encoding genes and were eaeA positive. Only 9 of 13 isolates from human controls were stx1+ stx2+, and 8 carried the eaeA gene. Comparison of profiles obtained by PFGE of XbaI-digested genomic DNA showed a great diversity among the E. coli O157 isolates, with 37 different profiles among 39 isolates analyzed. Cluster analysis of PFGE profiles showed a wide distribution of clinical isolates obtained from HUS cases and asymptomatic individuals and a clonal relationship among O157 isolates obtained from HUS cases and pigs. Analysis of virulence genes showed that a correlation exists among strains with the genotype stx1+ stx2+ eae+ and pathogenic potential. A larger difference in the PFGE restriction patterns was observed among the EHEC strains of serogroups O26 and O111. These results indicate that several different EHEC clones circulate in Chile and suggest that pigs are an important animal reservoir for human infections by EHEC. Guidelines have been proposed for better practices in the slaughter of animals in Chile.