Challenges with Implementing Oral Exams in Post-Secondary Mathematics Courses

In this study, seven mathematics professors and instructors were interviewed to share their thoughts about implementing oral assessment in mathematics courses in Canada and the United States, where oral assessment in mathematics is not part of the educational system. Four out of seven mathematics professors and instructors were educated in Poland, Romania, Bosnia, and Ukraine, and they are currently teaching mathematics at a university in Canada. The other three professors were educated in Canada, Germany, and the United States, and they are currently teaching at a university in Germany. Five participants had previously experienced oral examination in mathematics, while the other two had never been exposed to oral examination in mathematics throughout their schooling. The results showed that implementing oral assessment in mathematics courses at the university level in Canada and the United States might raise some students’ and professors’ concerns

Beliefs about Mathematics and Mathematics Assessment in Post-Secondary Education

This paper studied the beliefs about mathematics, mathematics assessment, and written and oral mathematics assessment in post-secondary education from the mathematics professors’ perspectives. Seven mathematics professors and instructors were interviewed and asked to explain how they perceive mathematics and mathematics assessment and how they compare the oral exam to the written exam. Four out of seven mathematics professors and instructors were educated in Poland, Romania, Bosnia, and Ukraine, and they are currently teaching mathematics at a university in Canada. The other three professors were educated in Canada, Germany, and the United States, and they are currently teaching at a university in Germany. Five participants had previously experienced an oral examination in mathematics, while the other two had never been exposed to an oral examination in mathematics throughout their schooling. The results showed that similar beliefs about mathematics and mathematics assessment result in different beliefs about written and oral mathematics assessment.

Mathematics professors\u27 views on written and oral assessment in mathematics

One of the most striking differences between the Canadian educational system and the European educational systems is the importance given to oral assessment, particularly in mathematics courses. This thesis studies the views on oral assessment in post-secondary education from mathematics professors’ perspectives. Seven mathematics professors and instructors are interviewed, being asked to explain how they perceive the oral examination, and how they compare the oral exam to the written exam. Four out of seven mathematics professors and instructors were educated in Poland, Romania, Bosnia, and Ukraine, and they are currently teaching mathematics at a university in Canada. The other three professors were educated in Canada, Germany, and the United States, and they are currently teaching at a university in Germany. Five participants had previously experienced oral examination in mathematics while the other two had never been exposed to oral examination in mathematics throughout their schooling. The results show that similar beliefs about mathematics result in different beliefs about mathematics assessment. They suggest that the mathematics professors’ views on oral assessment in mathematics are influenced by their schooling and teaching experiences with mathematics assessment, as well as the socio-cultural and the institutionalized mathematics assessment norms that exist within the teaching institution

Commentary on Paul Ernest’s Theory about Teachers’ Beliefs and Practice

In this short communication, the author analyzed Paul Ernest’s theory on relationships between teachers’ beliefs, and their impact on teachers’ practice of mathematics. The author considered the teachers’ espoused and enacted models of mathematics assessment in addition to the teachers' views of the nature of mathematics, teaching, and learning models. The author also considered three purposes of mathematics assessment

Surface characterization of amorphous hydrogenated carbon thin films containing nanoclusters of noble metals

In this work nanocomposite thin films of amorphous hydrogenated carbon (a-C:H) doped with noble transition metals of 1B group (gold, silver, and copper) are studied. The composite materials are obtained by combined magnetron sputtering (MS) of a metal target by argon, and plasma-assisted chemical vapor deposition (PACVD) of methane under vacuum conditions. Particular attention is devoted to the low metal-content a-C:H samples, in which metallic inclusions have a form of isolated nanoclusters. Our aim was to reveal surface cluster arrangement, i.e. to figure out whether topmost metallic nanoclusters are covered with a layer of a-C:H or are bald on the surface and hence exposed to the surrounding environment. We deposited our samples onto substrates kept on the ground potential and on �150 V dc bias voltage. The differences encountered in the surface structure and nanocluster arrangement between samples, which differed in the deposition process in this parameter only, provided an answer to the question of surface clusters coverage. The experimental techniques used to reach this goal comprised in vacuo and ex vacuo photoelectron spectroscopy (PES), direct imaging by atomic force microscopy (AFM) and scanning electron microscopy (SEM), and grazing incidence smallangle x-ray scattering (GISAXS). The majority of work is made in several photoemission experiments, using both x-ray and UV-excited photoelectron spectroscopy (XPS and UPS, respectively). In the course of the work, series of (grounded only) a-C:H/Au, a-C:H/Ag, and a-C:H/Cu samples, with metallic content varying from zero to 100 at.%, have been deposited and studied in vacuo by XPS and UPS (Section 3.1). The XPS results of these series show that, with decreasing metal content below the percolation threshold (at about 40-50 at.% of metal concentration), a shift in binding energy (BE) of metal core levels towards higher BEs is observed. With non-carbidic metals like the ones we used in our work, these shifts can be related to their isolated cluster structure in the host matrix. Decrease of the total metal content in the sample is followed by the decrease in the cluster size, which is reflected in increased binding energy of electrons escaping from them (Paragraph 2.2.2 and Section 3.1). At the same time, carbon C 1s core level is shifted in the opposite direction, towards lower binding energies, and this shift rises as metal content increases in the sample. Negative shift in C 1s binding energy reveals increased relative content of sp2-coordinated carbon in the a-C:H matrix, which, we believe, should be attributed to the compressive stress that metallic inclusions introduce in the host a-C:H, being higher with higher metal content in the sample. Another possible reason is catalytic reduction of hydrogen in the a-C:H matrix with increasing metallic content. UPS of the same series (Fig. 3.2) showed increased relative contribution of metal valence band features with increased metal content. The Fermi edge evolution from monocrystalline metal reference samples to low metal-content a-C:H showed both decrease in the density of states near the Fermi level and its shift to the higher BEs, related to the cluster structure of metallic inclusions and to the same direction-shifts in metal core levels. Our further attention was focused on low metal-content a-C:H that is, typically below 10 at.%, and to the differences between grounded and biased samples. The reprint of the communication on these effects encountered in a-C:H/Au and published in the Applied Physics Letters (Vol. 80, 2002, p.2863) is given in Section 3.2. Direct imaging techniques (Sections 3.2 and 3.3) reveal that even small amount of metal included in the a-C:H significantly changes the surface morphology and increases roughness. For all three nanocomposite materials, biased samples show similar surface morphology, characterized by relatively flat basis and isolated bump structures, of about 30 nm in diameter and up to 15 nm in height. These structures are attributed to the altered morphology of a-C:H component of a nanocomposite, with metallic clusters concentrated on them. Grounded samples characterize low roughness in a-C:H/Au and increased in a-C:H/Ag and a-C:H/Cu. The increase of roughness in the latter two materials is explained by enhanced surface diffusion of metal atoms and clusters coalescence into bigger islands. GISAXS patterns (Section 3.4) showed isotropic cluster size and intercluster distance distribution in grounded a-C:H/Au and a-C:H/Cu samples. With grounded a- C:H/Ag sample, no spatial correlation could be revealed, probably again due to the surface agglomeration of Ag clusters. These analysis of GISAXS patterns showed that biased samples contain bigger clusters than grounded ones, and slightly flattened in the grow direction. The differences between grounded and biased samples were first detected by in vacuo XPS of a-C:H/Au in systematically lower, in average about 50%, Au content in the biased than in the grounded case. This decrease is followed by higher positive shift of the Au 4f7/2 core level binding energy in the biased case (Section 3.2 and Paragraph 3.5.1). The similar situation was encountered in a-C:H/Ag samples, while a-C:H/Cu showed higher Cu content in the biased than in the grounded case and no difference in Cu 2p3/2 shifts from the reference BE. The decrease of the total metal content in biased a-C:H/Au and a-C:H/Ag samples most probably results from increased distance among surface clusters and their concentration on isolated bump structures. The reason for the increased BE shift of Au 4f7/2 and Ag 3d5/2 core levels in the biased samples should be searched in cluster baldness at the sample surface. The violation of both above conclusions in a-C:H/Cu, i.e. higher Cu content in the biased sample and equal shift of the Cu 2p3/2 core level in grounded and biased sample is probably due to high relative increase of copper cluster size upon biasing, which compensates the effect of their baldness at the surface. The topmost clusters of grounded nanocomposite samples are, therefore, most probably covered with a layer of a-C:H. The thickness of this layer must be below escape depth of metaloriginated photoelectrons, i.e. less than about 2 nm. The negative shift of the C 1s core level in the biased samples is induced by increased sp2/sp3 coordinated carbon ratio due to the sample bombardment by Ar+ ions during the deposition process. To our belief, the same effect is responsible for surface metallic clusters baldness in the biased samples. These conclusions are supported by several following PES experiments, other than XPS of as-deposited samples. First of them was in vacuo UPS of as-deposited samples. In the grounded samples, the He I spectra mostly reproduce the characteristic shape of a-C:H valence band, and only higher sensitivity He II UPS reveal the presence of metallic inclusions. Upon biasing, even when total measured metal content was lower than in the grounded case (a-C:H/Au and a-C:H/Ag), all spectra clearly showed increased metallic features, evidencing on higher metal exposure at the surface. XPS at off-normal take-off angle of escaping electrons also confirmed our conclusions on the surface clusters coverage. Increasing the tilting angle of a sample, measured intensity ratio of a metal core level to appropriate C 1s showed in most grounded samples monotonous decrease, and regular and steady increase in the biased ones. These results support our conclusion on the surface clusters coverage in grounded samples and their baldness in the biased ones. The higher metalcontent grounded samples of a-C:H/Ag, however, did not show the expected decrease in the intensity ratio, and that was the first indication that the effect of coverage may be a particularity of small clusters only, i.e. low-metal content grounded samples. This suspicious is confirmed in the next test experiment that we have undertaken, by subsequent in situ low-energy Ar+ ion etching and PES analysis of a sample. The same metal to carbon core level intensity ratio curves were measured against the sputtering time. In the grounded samples, at the beginning of the sputtering, an increase in the intensity ratio is observed, related to the thinning of the top a-C:H layer. In most cases, after some time of sputtering, the maximum is reached related to the total removal of the cover layer, and from that point onwards, Ar+ ion etching erodes the metallic clusters as well. In biased samples, a monotonous decrease of intensity ratio curves was observed throughout the experiment and is clearly related to the bald surface clusters that are sputtered together with the a-C:H matrix. The grounded samples intensity ratio curves showed one more important regularity: in higher metal-content samples the maximum is reached after shorter time, i.e. these samples need less time to be fully uncovered. As a special case, a- C:H/Ag 32.3 at.% did not show any increase in the intensity ratio curve, but monotonous decrease throughout the measurement. That encouraged the conclusion that the coverage of the topmost metallic clusters of grounded samples with a-C:H is an effect that is characteristics of small clusters in the host matrix, i.e. low metal-content samples. With higher metal contents, there is no observable difference between grounded and biased samples regarding surface clusters coverage. Apart from the core level intensity ratio curves, the evolution of our samples with in situ Ar+ ion etching is described in XPS and UPS spectra recorded at each point of the sputtering time scale. Metal core levels in these figures remained either unchanged or are slightly shifted towards higher binding energies. In the grounded samples, this is related to the thinning of the cover layer, and in the biased ones to the decrease of the cluster size by Ar+ ion sputtering. Carbon C 1s core level in all samples shows shift with sputtering time towards lower binding energies, which is related to the further sp2-coordinated carbon favoring by the in situ Ar+ ion bombardment. The UPS spectra evolution generally follows the trend described by core level intensity ratio curves. That is, in grounded samples, the metal features in valence band spectra rise to the point of total removal of the cover layer, and decrease further to the end of the sputtering experiment. Biased samples, on the other hand, show continuous decrease of the metal features. In both grounded and biased valence band spectra, the development of the carbon π-states is observed throughout the experiment, evidencing on the increase of sp2-coordinated carbon content with sputtering time. Pointed out several times, the Ag surface clusters coalescence is confirmed in experiment in which we compared XPS and UPS spectra of as-deposited samples, after 20 hours residence in the ultra-high vacuum (UHV) conditions and after additional 20 hours in the air. Generally, all as-deposited spectra and after 20 hours in the UHV were almost identical. After exposure to the air, in all samples carbon C 1s core level is shifted towards lower binding energies. The most interesting differences after residence in the air show metal core levels. The Au 4f7/2 core level remained practically identical to the one measured in the UHV, revealing that air conditions do not affect Au clusters, and that their size and arrangement remain fully determined by the deposition process. That is not the case, however, with Ag clusters. The Ag 3d5/2 core levels of both grounded and biased a-C:H/Ag samples shift towards lower binding energies. From the differences in UHV- and air-residence binding energy positions of the Ag 3d5/2, it is estimated that the increase factor of cluster volume in grounded samples is about 170, and the one of biased samples clusters � about 12. In these rough figures one may find the cause of the specific behavior of the a-C:H/Ag sample that we encountered in several occasions and assigned to the Ag surface clusters coalescence: roughness revealed by AFM, lack of correlation in the GISAXS patterns, pronounced Ag 4d features even in low metal content valence band spectra, and negative shift of the Ag 3d5/2 in the Ar+ ion in situ in-depth profiling. The last of our nanocomposites subjected to UHV- and air-dwell comparison was a- C:H/Cu. Copper, however, oxidizes in the air, but nevertheless it provided in this experiment one of most elegant evidences on the surface clusters coverage. The deconvolution procedure applied to copper- and CuO-originated Cu 2p3/2 revealed that relative content of oxidized copper is higher on the surface of biased sample (with bald surface clusters), than on the grounded one (where surface clusters are covered by a-C:H). The last in the series of experiments aimed to check our conclusions on the surface clusters coverage was based on the prospective sulfur binding to noble metal atoms. Our samples, together with appropriate monocrystalline reference samples, were covered with a layer of liquid thiophene (C4H4S) and, after evaporation, subjected again to the XPS analysis. The total amount of adsorbed sulfur was generally low, about 5 at.% or less. That results in noisy XPS spectra of the S 2p core levels region, in spite of increased measurement statistics. The S 2p spectra adsorbed on the reference samples were fitted with three S 2p1/2 � S 2p3/2 doublets assigned to S bonds to a noble metal, S in C4H4S, and to S�O bonds (Figs. 3.32-3.34). Intercomparison of our nanocomposite samples with reference ones showed that sulfur adsorbed on surfaces originates predominantly from C4H4S itself. However, in biased cases a higher relative contribution of the shoulder related to sulfur bonds to a noble metal is observed in spectra, evidencing on higher metal exposure at the biased samples surfaces. The exception of a-C:H/Cu is due to the oxidation of copper. In conclusion, in several different PES experiments, by direct imaging of samples, and using GISAXS technique, we have revealed that MS/PACVD-obtained low noble metal-content amorphous hydrogenated carbon nanocomposites are characterized with topmost metallic clusters covered with a tiny layer of a-C:H when deposited on a grounded substrate, and bald surface clusters when substrate is biased with �150 V dc. Beside this main result, we encountered few other effects, like e.g. increased sp2/sp3 coordinated carbon ratio in the a-C:H matrix in the biased samples and surface clusters coalescence in a-C:H/Ag (and to some extent in a-C:H/Cu) nanocomposites. By changing one parameter only � the substrate bias voltage in deposition of our grounded and biased �counterparts�, we have shown that surface clusters coverage effect has an origin in the plasma deposition process itself. We believe that one should look for its cause in the plasma afterglow, the state established in the ionized gas immediately after switching off the plasma power supply. From the applicative point of view, we have described, in principle, the mechanism that may be employed to tailor the coverage of topmost metallic clusters embedded in the a-C:H matrix. Metal inclusions in the a-C:H showed to improve the wear resistance of the coatings, so one can also envisage the applications when the coverage of surface metal clusters with a-C:H would be useful. In tribology, these would be cases when incorporated metal reduces the lubricating properties, i.e. increases the friction coefficient. In biocompatible materials the same would be necessary when incorporated metals are toxic, like e.g. silver or copper. Vice versa, one may also envisage applications when topmost cluster baldness would be desirable, like e.g. with low-friction MoS2 and WS2 inclusions in a-C:H for tribological purposes. In addition, surface clusters exposure to the surrounding environment probably influences the optical and aging properties of solar selective coatings based on metal- or metal carbide-containing amorphous hydrogenated carbon nanocomposites

Femoral artery blowout syndrome following radical vulvectomy and radiation therapy

Arterial blowout syndrome has mostly been described in carotid arteries and has been attributed to factors associated with head and neck neoplasia, radical resection, and a history of irradiation. Only sporadic cases have been described in other arteries. Herein we present a case of the femoral artery blowout syndrome, six months after radical surgery of the vulva and radiation therapy

Light Therapy in Parkinson's Disease: Towards Mechanism-Based Protocols

Circadian clocks in health and diseas

Comparison of Feedback Influence on Ring Oscillator Performance for IR-UWB Pulse Generator in 0.13 μm and 0.18 μm CMOS Technologies

Part 20: Electronics: RF ApplicationsInternational audienceA CMOS three-stage ring oscillator is examined in UMC 0.13 μm and 0.18 μm technologies. The influence of PMOS transistor and resistor, as inverter feedbacks, on the ring oscillator frequency and the peak-to-peak amplitude is investigated in both technologies. Furthermore, as the ring oscillator usually drives a buffer in pulse generator/transmitter chain, dependence of its Figures of Merit on the buffer feedback is presented in the paper. Simulation results showed that the ring oscillator frequency is strongly dependent on the inverter feedback. The presented techniques can be used to increase (resistive feedback) and control (PMOS transistor feedback) the ring oscillator frequency. As the ring oscillator is a part of an IR-UWB (Impulse Radio Ultra Wide Band) pulse generator, its oscillating frequency determines the spectrum central frequency and has significant effect on spectrum fitting within UWB FCC mask

Fosmetpantotenate Randomized Controlled Trial in Pantothenate Kinase–Associated Neurodegeneration

Fosmetpantotenate; Randomized controlled trialFosmetpantotenato; Ensayo controlado aleatorizadoFosmetpantotenat; Assaig controlat aleatoritzatBackground Pantothenate kinase–associated neurodegeneration (PKAN) currently has no approved treatments. Objectives The Fosmetpantotenate Replacement Therapy pivotal trial examined whether treatment with fosmetpantotenate improves PKAN symptoms and stabilizes disease progression. Methods This randomized, double-blind, placebo-controlled, multicenter study evaluated fosmetpantotenate, 300 mg oral dose three times daily, versus placebo over a 24-week double-blind period. Patients with pathogenic variants of PANK2, aged 6 to 65 years, with a score ≥6 on the PKAN-Activities of Daily Living (PKAN-ADL) scale were enrolled. Patients were randomized to active (fosmetpantotenate) or placebo treatment, stratified by weight and age. The primary efficacy endpoint was change from baseline at week 24 in PKAN-ADL. Results Between July 23, 2017, and December 18, 2018, 84 patients were randomized (fosmetpantotenate: n = 41; placebo: n = 43); all 84 patients were included in the analyses. Six patients in the placebo group discontinued treatment; two had worsening dystonia, two had poor compliance, and two died of PKAN-related complications (aspiration during feeding and disease progression with respiratory failure, respectively). Fosmetpantotenate and placebo group PKAN-ADL mean (standard deviation) scores were 28.2 (11.4) and 27.4 (11.5) at baseline, respectively, and were 26.9 (12.5) and 24.5 (11.8) at week 24, respectively. The difference in least square mean (95% confidence interval) at week 24 between fosmetpantotenate and placebo was −0.09 (−1.69 to 1.51; P = 0.9115). The overall incidence of treatment-emergent serious adverse events was similar in the fosmetpantotenate (8/41; 19.5%) and placebo (6/43; 14.0%) groups. Conclusions Treatment with fosmetpantotenate was safe but did not improve function assessed by the PKAN-ADL in patients with PKAN.The FORT trial was supported by Retrophin, Inc