pinecone/core-2020-05-10-deduplication huggingface dataset:
Student perspectives on group work in support of the learning of mathematics at high school and at a university of technology

This is an Accepted Manuscript of an article published by Taylor & Francis in African Journal of Research in Mathematics, Science and Technology Education on 20 August 2013, available online: http://www.tandfonline.com/10.1080/10288457.2010.10740681.Debates on improving performance in science and engineering at higher education institutions have stressed the need for institutions to adopt pedagogic practices appropriate for the setting. In this paper we contribute to this debate by presenting the results of empirical research conducted in a first-year foundation mathematics course for Civil Engineering students at a University of Technology in South Africa. Using the perspective of learning as participation in a community as a theoretical framework, the paper focuses on a particular type of student learning community, that is, small group work for the learning of mathematics. We use individual interviews to investigate students' perspectives on small group work in support of their learning of mathematics at high school and in the foundation mathematics course. The results suggest that students have considerable experience of working in groups inside and outside the classroom at school, and they identify conditions conducive for group work, including having a sense of belonging in a group. They value group work for providing support that may not be provided by the lecturer, for example, by obtaining alternative explanations (often in their home language), sharing ideas on problem solving, and getting immediate feedback. We argue that higher education institutions should draw on students' experience of group work and create the space for this type of student learning community both inside and outside the mathematics classroom. We also use the empirical results to develop the notion of “community” as described in the theoretical perspective of learning
N,N'-Ethylenebis(pyridoxylideneiminato) and N,N'-Ethylenebis(pyridoxylaminato): Synthesis, Characterization, Potentiometric, Spectroscopic, and DFT Studies of Their Vanadium(IV) and Vanadium(V) Complexes

The Schiff base N,Nprime-ethylenebis(pyridoxylideneiminato) (H2pyr2en, 1) was synthesized by reaction of pyridoxal with ethylenediamine; reduction of H2pyr2en with NaBH4 yielded the reduced Schiff base N,Nprime-ethylenebis(pyridoxylaminato) (H2Rpyr2en, 2); their crystal structures were determined by X-ray diffraction. The totally protonated forms of 1 and 2 correspond to H6L4+, and all protonation constants were determined by pH-potentiometric and 1H NMR titrations. Several vanadium(IV) and vanadium(V) complexes of these and other related ligands were prepared and characterized in solution and in the solid state. The X-ray crystal structure of [VVO2(HRpyr2en)] shows the metal in a distorted octahedral geometry, with the ligand coordinated through the N-amine and O-phenolato moieties, with one of the pyridine-N atoms protonated. Crystals of [(VVO2)2(pyren)2]sdot2 H2O were obtained from solutions containing H2pyr2en and oxovanadium(IV), where Hpyren is the ldquohalfrdquo Schiff base of pyridoxal and ethylenediamine. The complexation of VIVO2+ and VVO2+ with H2pyr2en, H2Rpyr2en and pyridoxamine in aqueous solution were studied by pH-potentiometry, UV/Vis absorption spectrophotometry, as well as by EPR spectroscopy for the VIVO systems and 1H and 51V NMR spectroscopy for the VVO2 systems. Very significant differences in the metal-binding abilities of the ligands were found. Both 1 and 2 act as tetradentate ligands. H2Rpyr2en is stable to hydrolysis and several isomers form in solution, namely cis-trans type complexes with VIVO, and alpha-cis- and beta-cis-type complexes with VVO2. The pyridinium-N atoms of the pyridoxal rings do not take part in the coordination but are involved in acid-base reactions that affect the number, type, and relative amount of the isomers of the VIVO-H2Rpyr2en and VVO2-H2Rpyr2en complexes present in solution. DFT calculations were carried out and support the formation and identification of the isomers detected by EPR or NMR spectroscopy, and the strong equatorial and axial binding of the O-phenolato in VIVO and VVO2 complexes. Moreover, the DFT calculations done for the [VIVO(H2Rpyr2en)] system indicate that for almost all complexes the presence of a sixth equatorial or axial H2O ligand leads to much more stable compounds.http://dx.doi.org/10.1002/chem.20030531
Development and Application of Oxysilane Sol-Gel Electrochemical Glucose Biosensors Based on Cobalt Hexacyanoferrate Modified Carbon Film Electrodes

The evaluation and characterization of a new glucose oxidase (GOx) electrochemical enzyme biosensors on a carbon film electrode support and using two types of sol-gel precursor mixture for enzyme immobilization was carried out in order to be employed as a short-time-use or as a disposable sensor. Carbon film electrodes were modified with films of CoHCF mediator by potential cycling. The sol-gel was prepared using a combination of 3-glycidoxypropyltrimethoxysilane (GOPMOS) with methyltrimethoxysilane (MTMOS) or tetraethoxysilane (TEOS).http://dx.doi.org/10.1002/elan.20060371
Frictional behavior of self-adaptive nanostructural Mo–Se–C coatings in different sliding conditions

Sliding properties of Mo–Se–C coatings with two different carbon content deposited by magnetron sputtering were investigated in different sliding environments (argon, nitrogen, dry and humid air). Both coatings had a structure that was identified as randomly oriented structures of MoSe2 embedded into amorphous carbon matrix. The worn surfaces, i.e. the wear tracks and the wear scars of the balls, were analyzed by optical microscopy, Raman spectroscopy and scanning electron microscopy. The material transferred to the ball steel surfaces was almost exclusively MoSe2, whereas the wear tracks on the coatings were more complex, with areas rich in MoSe2 and areas similar to that of as-deposited coatings.

The friction was lowest in argon (0.012 at a load of 10 N) and highest in humid air, but still remarkably low; as best 0.05 at 10 N load; however, the exceptionally low wear rate was almost identical. Thus, we focused our detailed analysis on these two examples to understand the mechanisms responsible for the difference between the friction coefficients. SEM, EDX, XPS, Raman and TEM with EELS and EDX were applied to investigate the composition and structure of localized spots of interest on the tested surfaces. In both cases, we observed well-ordered MoSe2 tribofilms with negligible amount of oxides. Carbon was not present in the sliding interfaces, although large amount of carbon was found outside the contacts on both surfaces. Based on our investigations, we suggest the increase in friction of Mo–Se–C in humid air is primarily due to the increase in shear strength of the MoSe2 structure by the presence of water molecules in the sliding interface
Genidentity and Biological Processes

A crucial question for a process view of life is how to identify a process and how to follow it through time. The genidentity view (first proposed by Kurt Lewin and later elaborated by Hans Reichenbach) can contribute decisively to this project. It says that the identity through time of an entity X is given by a well-identified series of continuous states of affairs. Genidentity helps address the problem of diachronic identity in the living world. This chapter describes the centrality of the concept of genidentity for David Hull and proposes an extension of Hull’s view to the ubiquitous phenomenon of symbiosis. Finally, using immunology as a key example, it shows that the genidentity view suggests that the main interest of a process approach is epistemological rather than ontological and that its principal claim is one of priority, namely that processes precede and define things, and not vice versa
Artificial pancreas using a personalized rule-based controller achieves overnight normoglycemia in patients with type 1 diabetes

Objective: This study assessed the efﬁcacy of a closed-loop (CL) system consisting of a predictive rule-based algorithm\ud
(pRBA) on achieving nocturnal and postprandial normoglycemia in patients with type 1 diabetes mellitus (T1DM). The\ud
algorithm is personalized for each patient’s data using two different strategies to control nocturnal and postprandial periods.\ud
Research Design and Methods: We performed a randomized crossover clinical study in which 10 T1DM patients treated with continuous subcutaneous insulin infusion (CSII) spent two nonconsecutive nights in the research facility: one with their usual CSII pattern (open-loop [OL]) and one controlled by the pRBA (CL). The CL period lasted from 10 p.m. to 10 a.m., including overnight control, and control of breakfast. Venous samples for blood glucose (BG) measurement were collected every 20 min.\ud
Results: Time spent in normoglycemia (BG, 3.9–8.0 mmol/L) during the nocturnal period (12 a.m.–8 a.m.), expressed as\ud
median (interquartile range), increased from 66.6% (8.3–75%) with OL to 95.8% (73–100%) using the CL algorithm (P<0.05).\ud
Median time in hypoglycemia (BG, <3.9 mmol/L) was reduced from 4.2% (0–21%) in the OL night to 0.0% (0.0–0.0%) in the\ud
CL night (P<0.05). Nine hypoglycemic events (<3.9 mmol/L) were recorded with OL compared with one using CL. The\ud
postprandial glycemic excursion was not lower when the CL system was used in comparison with conventional preprandial\ud
bolus: time in target (3.9–10.0 mmol/L) 58.3% (29.1–87.5%) versus 50.0% (50–100%).\ud
Conclusions: A highly precise personalized pRBA obtains nocturnal normoglycemia, without signiﬁcant hypoglycemia, in\ud
T1DM patients. There appears to be no clear beneﬁt of CL over prandial bolus on the postprandial glycemi
Flavor-Symmetry Restoration and Symanzik Improvement for Staggered
  Quarks

We resolve contradictions in the literature concerning the origins and size
of unphysical flavor-changing strong interactions generated by the
staggered-quark discretization of QCD. We show that the leading contributions
are tree-level in $\order(a^2)$ and that they can be removed by adding three
correction terms to the link operator in the standard action. These corrections
are part of the systematic Symanzik improvement of the staggered-quark action.
We present a new improved action for staggered quarks that is accurate up to
errors of $\order(a^4,a^2\alpha_s)$ --- more accurate than most, if not all,
other discretizations of light-quark dynamics.Comment: 7 page
Inverse Consistency Error in the Registration of Prone and Supine Images in CT Colonography

Robust registration between prone and supine data acquisitions for CT colonography is pivotal for medical interpretation but a challenging problem. One measure when evaluating non-rigid registration algorithms over the whole of the deformation field is the inverse consistency error, which suggests improved registration quality when the inverse deformation is consistent with the forward deformation. We show that using computed landmark displacements to initialise an intensity based registration reduces the inverse consistency error when using a state-of-the-art non-rigid b-spline registration method. This method aligns prone and supine 2D images derived from CT colonography acquisitions in a cylindrical domain. Furthermore, we demonstrate that using the same initialisation also improves registration accuracy for a set of manually identified reference points in cases exhibiting local luminal collapse
Multiscale modeling of upper mantle plasticity: From single-crystal rheology to multiphase aggregate deformation

We report a first application of an improved second-order (SO) viscoplastic self-consistent model for multiphase aggregates, applied to an olivine + diopside aggregate as analogue for a dry upper mantle peridotite deformed at 10 15 s 1 shear strain rate along a 20-Ma ocean geotherm. Beside known dislocation slip systems, this SO-model version accounts for an isotropic relaxation mechanism representing ‘diffusionrelated’ creep mechanisms in olivine. Slip-system critical resolved shear stress (CRSS) are evaluated in both phases – as functions of P, T, oxygen fugacity (fO2) and strain rate – from previously reported experimental data obtained on single crystals and first-principle calculations coupled with the Peierls–Nabarro model for crystal plasticity; and the isotropic-mechanism dependence on T and P matches that of Si selfdiffusion in olivine, while its relative activity is constrained by reported data. The model reproduces well the olivine and diopside lattice preferred orientations (LPO) produced experimentally and observed in naturally deformed rocks, as well as observed sensitivities of multiphase aggregate strength to the volume fraction of the hard phase (here diopside). It shows a significant weakening of olivine LPO with increasing depth, which results from the combined effects of the P-induced [100]/[001] dislocation-slip transition and the increasing activity with T of ‘diffusion-related’ creep. This work thus provides a first quantification of the respective effects of [100]/[001] slip transition and diffusion creep on the olivine LPO weakening inducing the seismic anisotropy attenuation observed in the upper mantle
A study of composite material damage induced by laser shock waves

A laser shock wave technique has been used to study the damage tolerance of T800/M21 CFRP (Carbon Fiber Reinforced Polymer) composite material with different lay_ups. Different levels of damage have been created according to various laser irradiation conditions. Several characterization methods such as Optical Microscopy, X-ray Radiography, or Interferometric Confocal Microscopy have been used to quantify these defects. The nature of the defects induced by the shock wave propagation has been studied. The sensitivity of the composite material damage to the shock conditions has been shown and quantified. Moreover, the experimental results gathered with each technique have been compared to each other and it leads to a better understanding of the CFRP behavior under high dynamic loading. These original results have enabled the definition of a specific damage criterion for CFRP under dynamic loading
Dispersion of carbon nanotubes in polypropylene via multilayer coextrusion: Influence on the mechanical properties

The authors would like to thank PSA for funding this research and providing some of the materials used in this study. We also would like to thank R. Glénat, P. Soria, E. Dandeu, A. Grand- montagne and A. Dubruc for their help in the preparation and the optical and mechanical characterizations of the samples presented in this study.Multilayer coextrusion was used to disperse Carbon Nanotubes (CNT) in polypropylene (PP). The dilution  of commercially available masterbatches using a twin-screw extruder was first applied to produce several formulations, which were then mixed with PP using a multilayer coextrusion device to obtain films or pellets with CNT concentrations between 0.1 and 1%wt. The influence of the specific mechanical energy (SME) during the dilution step, of the addition of a compatibilizer, and of the multilayer tool on the CNT dispersion within the matrix was highlighted. The effect of the dispersion on the thermomechanical properties of the resulting materials was studied. We showed notably that films containing 0.2%wt CNT, 1%wt of PPgAm, prepared at high SME presented a Young’s modulus increase of 25e30% without significant decrease in the elongation at break. These results, using low amounts of CNT and industrially available devices, may show a new path for producing nanocomposites
Micromechanical investigation of the influence of defects in high cycle fatigue

This study aims to analyse the influence of geometrical defects (notches and holes) on the high cycle fatigue behaviour of an electrolytic copper based on finite element simulations of 2D polycrystalline aggregates. In order to investigate the role of each source of anisotropy on the mechanical response at the grain scale, three different material constitutive models are assigned successively to the grains: isotropic elasticity, cubic elasticity and crystal plasticity in addition to the cubic elasticity. The significant influence of the elastic anisotropy on the mechanical response of the grains is highlighted. When considering smooth microstructures, the crystal plasticity have has a slight effect in comparison with the cubic elasticity influence. However, in the case of notched microstructures, it has been shown that the influence of the plasticity is no more negligible. Finally, the predictions of three fatigue criteria are analysed. Their ability to predict the defect size effect on the fatigue strength is evaluated thanks to a comparison with experimental data from the literature
Upper ocean vertical supply: A neglected primary factor controlling the distribution of neodymium concentrations of open ocean surface waters?

Neodymium (Nd) isotopes are an important geochemical tool to trace the present and past water mass mixing as well as continental inputs. The distribution of Nd concentrations in open ocean surface waters (0â��100 m) is generally assumed to be controlled by lateral mixing of Nd from coastal surface currents and by removal through reversible particle scavenging. However, using 228Ra activity as an indicator of coastal water mass influence, surface water Nd concentration data available on key oceanic transects as a whole do not support the above scenario. From a global compilation of available data, we find that more stratified regions are generally associated with low surface Nd concentrations. This implies that upper ocean vertical supply may be an as yet neglected primary factor in determining the basin-scale variations of surface water Nd concentrations. Similar to the mechanism of nutrients supply, it is likely that stratification inhibits vertical supply of Nd from the subsurface thermocline waters and thus the magnitude of Nd flux to the surface layer. Consistently, the estimated required input flux of Nd to the surface layer to maintain the observed concentrations could be nearly two orders of magnitudes larger than riverine/dust flux, and also larger than the model-based estimation on shelf-derived coastal flux. In addition, preliminary results from modeling experiments reveal that the input from shallow boundary sources, riverine input, and release from dust are actually not the primary factors controlling Nd concentrations most notably in the Pacific and Southern Ocean surface waters
The impact of the economic crisis and policy actions on GHG emissions from road transport in Spain

Road traffic is the greatest contributor to the carbon footprint of the transport sector and reducing it has become one of the main targets of sustainable transport policies. An analysis of the main factors influencing greenhouse gas (GHG) emissions is essential for designing new energy- and environmentally efficient strategies for the road transport. This paper addresses this need by (i) identifying factors which influence the carbon footprint, including traffic activity, fuel economy and socioeconomic development; and (ii) proposing a methodological framework which uses Modified Laspeyres Index decomposition to analyze the effect of important drivers on the changes in emissions of road transport in Spain during the period from 1990 to 2010. The results demonstrate that the country׳s economic growth has been closely linked to the rise in GHG emissions. The innovative contribution of this paper is the special analysis of the changes in mobility patterns and GHG emissions during the economic crisis, when, for the first time, Spanish road traffic emissions decreased. The reduction of road transport and improved energy efficiency has been powerful contributors to this decrease, demonstrating the effectiveness of energy-saving measures. On the basis of this analysis, several tailored policy recommendations have been suggested for future implementation
Atmospheric parameters, spectral indexes and their relation to CPV spectral performance

Air Mass and atmosphere components (basically aerosol (AOD) and precipitable water (PW)) define the absorption of the sunlight that arrive to Earth. Radiative models such as SMARTS or MODTRAN use these parameters to generate an equivalent spectrum. However, complex and expensive instruments (as AERONET network devices) are needed to obtain AOD and PW. On the other hand, the use of isotype cells is a convenient way to characterize spectrally a place for CPV considering that they provide the photocurrent of the different internal subcells individually. Crossing data from AERONET station and a Tri-band Spectroheliometer, a model that correlates Spectral Mismatch Ratios and atmospheric parameters is proposed. Considering the amount of stations of AERONET network, this model may be used to estimate the spectral influence on energy performance of CPV systems close to all the stations worldwide
Understanding the correlation between ( g − 2) μ and μ → eγ in the MSSM

The supersymmetric contributions to the muon anomalous magnetic moment a μ and to the decay μ → eγ are given by very similar Feynman diagrams. Previous works reported correlations in specific scenarios, in particular if a μ is dominated by a single diagram. In this work we give an extensive survey of the possible correlations. We discuss examples of single-diagram domination with particularly strong correlations, and provide corresponding benchmark parameter points. We show how the correlations are weakened by significant cancellations between diagrams in large parts of the MSSM parameter space. Nevertheless, the order of magnitude of BR( μ → eγ ) for a fixed flavor-violating parameter can often be predicted. We summarize the behavior by plotting the correlations as well as resulting bounds on the flavor-violating parameters under various assumptions on the MSSM spectrum
Superspace de Rham complex and relative cohomology

We investigate the super-de Rham complex of five-dimensional superforms with N = 1 supersymmetry. By introducing a free supercommutative algebra of auxiliary variables, we show that this complex is equivalent to the Chevalley-Eilenberg complex of the translation supergroup with values in superfields. Each cocycle of this complex is defined by a Lorentz- and iso-spin-irreducible superfield subject to a set of constraints. Restricting to constant coefficients results in a subcomplex in which components of the cocycles are coboundaries while the constraints on the defining superfields span the cohomology. This reduces the computation of all of the superspace Bianchi identities to a single linear algebra problem the solution of which implies new features not present in the standard four-dimensional, N = 1 complex. These include splitting/joining in the complex and the existence of cocycles that do not correspond to irreducible supermultiplets of closed differential forms. Interpreting the five-dimensional de Rham complex as arising from dimensional reduction from the six-dimensional complex, we find a second five-dimensional complex associated to the relative de Rham complex of the embedding of the latter in the former. This gives rise to a second source of closed differential forms previously attributed to the phenomenon called “Weyl triviality”