"My personal relationship towards mathematics has necessarily not changed but..." : analyzing preservice teachers' mathematical identity talk

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UNRAVELING A NEW ROLE OF TFEB IN FILOPODIA FORMATION

The microphthalmia family (MITF, TFEB, TFE3, and TFEC) of transcription factors is emerging as global regulators of cancer cell survival and energy metabolism, both through the promotion of lysosomal genes as well as newly uncharacterized targets. During my Ph.D. thesis project, I revealed a new set of TFEB target genes that when activated could contribute to cell migration and invasiveness in cancer. During my work, I found that TFEB regulates the filopodial initiator's factors IRSp53 and EPS8 causing a change in cell shape and an increase in filopodia number that correlates with an augmented motility and invasiveness of the cell. On the contrary, depletion of TFEB and TFE3 leads to down-regulation of EPS8 and IRSp53, and a decrease of filopodia numbers. I confirmed the entire study in the Melanoma cell line (501Mel), a model of cancer, that are cells with a high degree of motility, showing that also in this system, there is an increase in the number of filopodia as well as of EPS8 and IRSp53 levels. This phenotype was completely reversed by depletion of MITF or TFEB and TFE3, demonstrating that the upregulation of these transcription factors could contribute to the invasive phenotype of melanoma cells. Altogether these data revealed a new role of MITF transcription factors as regulators of a transcriptional program that could control metastatic cancer initialization

Kinetics of the Reactions of CH2Cl, CH3CHCl, and CH3CCl2 Radicals with Cl2 in the Temperature Range 191-363 K

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Learning density of numbers in elementary teacher education

Infinity is an important concept in mathematics, which students find difficult to learn. This paper will report Finnish elementary teacher students’ understanding of density at the beginning of their studies and the development of that understanding during a mathematics methods course. The results show that even quite limited teaching can initiate significant improvement. Moreover, students can make progress even if their initial level of performance is low. Yet, only 60 % of elementary education students reach satisfactory content knowledge and pedagogical content knowledge by the end of the course.Peer reviewe

Theoretical and Experimental Investigation of Random Gust Loads Part I : Aerodynamic Transfer Function of a Simple Wing Configuration in Incompressible Flow

Sinusoidally oscillating downwash and lift produced on a simple rigid airfoil were measured and compared with calculated values. Statistically stationary random downwash and the corresponding lift on a simple rigid airfoil were also measured and the transfer functions between their power spectra determined. The random experimental values are compared with theoretically approximated values. Limitations of the experimental technique and the need for more extensive experimental data are discussed

Effect of Methyl Group Substitution on the Kinetics of Vinyl Radical + O-2 Reaction

The kinetics of (CH3)(2)CCH + O-2 (1) and (CH3)(2)CCCH3 + O-2 (2) reactions have been measured as a function of temperature (223-600 K) at low pressures (0.4-2 Torr) using a tubular laminar flow reactor coupled to a photoionization mass spectrometer (PIMS). These reactions are important for accurate modeling of unsaturated hydrocarbon combustion. Photolysis of a brominated precursor by a pulsed excimer laser radiation at 248 nm wavelength along the flow reactor axis was used for the production of radicals. The measured bimolecular rate coefficient of reaction 1 shows a negative temperature dependence over the temperature range 223-384 K and becomes temperature independent at higher temperatures. The bimolecular rate coefficient of reaction 2 exhibits a negative temperature dependence throughout the experimental temperature range. The bimolecular rate coefficients of reactions 1 and 2 are expected to be at the high-pressure limit under the current experimental conditions, and the following values are obtained at 298 K: k(1)(298 K) = (4.5 +/- 0.5) x 10(-12) cm(3) s(-1) and k(2)(298 = (8.9 +/- 1.0) x 10(-12) cm(3) s(-1). The observed products for reactions 1 and 2 were CH3COCH3 and CH3 + CH3COCH3, respectively. Substituting both beta-hydrogens in the vinyl radical (CH2CH) with methyl groups decreases the rate coefficient of the CH2CH + O-2 reaction by about 50%. However, the rate coefficient of the triply substituted (CH3)(2)CCCH3 radical reaction with O-2 is almost identical to the CH2CH + O-2 rate coefficient under the covered temperature range.Peer reviewe

Kinetics and thermochemistry of the reaction of 3-methylpropargyl radical with molecular oxygen

We have measured the kinetics and thermochemistry of the reaction of 3-methylpropargyl radical (but-2-yn-1-yl) with molecular oxygen over temperature (223-681 K) and bath gas density (1.2 - 15.0 x 10(16)cm(-3)) ranges employing photoionization mass-spectrometry. At low temperatures (223-304 K), the reaction proceeds overwhelmingly by a simple addition reaction to the -CH2 end of the radical, and the measured CH3CCCH2 center dot+O-2 reaction rate coefficient shows negative temperature dependence and depends on bath gas density. At intermediate temperatures (340-395 K), the addition reaction equilibrates and the equilibrium constant was determined at different temperatures. At high temperatures (465-681 K), the kinetics is governed by O-2 addition to the third carbon atom of the radical, and rate coefficient measurements were again possible. The high temperature CH3CCCH2 center dot +O(2 )rate coefficient is much smaller than at low T, shows positive temperature dependence, and is independent of bath gas density. In the intermediate and high temperature ranges, we observe a formation signal for ketene (ethenone). The reaction was further investigated by combining the experimental results with quantum chemical calculations and master equation modeling. By making small adjustments (2 - 3 kJ mol(-1)) to the energies of two key transition states, the model reproduces the experimental results within uncertainties. The experimentally constrained master equation model was used to simulate the CH3CCCH2 center dot+ O-2 reaction system at temperatures and pressures relevant to combustion. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.Peer reviewe

Temperature and Pressure Dependence of the Reaction between Ethyl Radical and Molecular Oxygen : Experiments and Master Equation Simulations

Funding Information: We thank Stephen Klippenstein for providing us with the geometries, harmonic frequencies, and relative energies of the stationary points from his recent CH + O publication as well as the state sum for the loose recombination transition state. T.T.P. acknowledges support from the Doctoral Programme in Chemistry and Molecular Sciences of the University of Helsinki and the Magnus Ehrnrooth Foundation for funding. Project K129140 for G.L. was implemented with the support provided by the Ministry of Innovation and Technology of Hungary from the National Research, Development and Innovation Fund, financed under the OTKA funding scheme. T.T.P., E.A.R., and A.J.E. acknowledge support from the Academy of Finland (Grants 325250 and 346374). The authors also acknowledge CSC IT Center for Science in Finland for computational resources. 2 5 • 2 Publisher Copyright: © 2023 The Authors.We have used laser-photolysis - photoionization mass-spectrometry to measure the rate coefficient for the reaction between ethyl radical and molecular oxygen as a function of temperature (190-801 K) and pressure (0.2-6 Torr) under pseudo first-order conditions ([He] >> [O2] >> [C2H5 center dot]). Multiple ethyl precursor, photolysis wavelength, reactor material, and coating combinations were used. We reinvestigated the temperature dependence of the title reaction's rate coefficient to resolve inconsistencies in existing data. The current results indicate that some literature values for the rate coefficient may indeed be slightly too large. The experimental work was complemented with master equation simulations. We used the current and some previous rate coefficient measurements to optimize the values of key parameters in the master equation model. After optimization, the model was able to reproduce experimental falloff curves and C2H4 + HO2 center dot yields. We then used the model to perform simulations over wide temperature (200-1500 K) and pressure (10-4-102 bar) ranges and provide the results in PLOG format to facilitate their use in atmospheric and combustion models.Peer reviewe

An experimental and master-equation modeling study of the kinetics of the reaction between resonance-stabilized (CH3)(2)CCHCH2 radical and molecular oxygen

The kinetics of the reaction between resonance-stabilized (CH3)(2)CCHCH2 radical (R) and O-2 has been investigated using photoionization mass spectrometry, and master equation (ME) simulations were performed to support the experimental results. The kinetic measurements of the (CH3)(2)CCHCH2 + O-2 reaction (1) were carried out at low helium bath-gas pressures (0.2-5.7 Torr) and over a wide temperature range (238-660 K). Under low temperature (238-298 K) conditions, the pressure-dependent bimolecular association reaction R + O-2 -> ROO determines kinetics, until at an intermediate temperature range (325-373 K) the ROO adduct becomes thermally unstable and increasingly dissociates back to the reactants with increasing temperature. The initial association of O-2 with (CH3)(2)CCHCH2 radical occurs on two distinct sites: terminal 1(t) and non-terminal 1(nt) sites on R, leading to the barrierless formation of ROO(t) and ROO(nt) adducts, respectively. Important for autoignition modelling of olefinic compounds, bimolecular reaction channels appear to open for the R + O-2 reaction at high temperatures (T > 500 K) and pressure-independent bimolecular rate coefficients of reaction (1) with a weak positive temperature dependence, (2.8-4.6) x 10(-15) cm(3) molecule(-1) s(-1), were measured in the temperature range of 500-660 K. At a temperature of 501 K, a product signal of reaction (1) was observed at m/z = 68, probably originating from isoprene. To explore the reaction mechanism of reaction (1), quantum chemical calculations and ME simulations were performed. According to the ME simulations, without any adjustment to energies, the most important and second most important product channels at the high temperatures are isoprene + HO2 (yield > 91%) and (2R/S)-3-methyl-1,2-epoxybut-3-ene + OH (yield isoprene + HO2 (similar to 2.2 kcal mol(-1)), the ME model was able to reproduce the experimental findings. Modified Arrhenius expressions for the kinetically important reaction channels are enclosed to facilitate the use of current results in combustion models.Peer reviewe

Kinetics and thermochemistry of the reaction of 1-methylpropargyl radicals with oxygen molecules : Experiments and computations

We have used laser-photolysis/photoionization mass spectrometry to measure the kinetics of the reaction of 1-methylpropargyl (but-3-yn-2-yl, CH C=CH-CH3) radicals with oxygen molecules as a function of temperature (T = 200 - 685 K) and bath gas density (1.2 - 15 x 10(16) cm(-3)). The low temperature (TPeer reviewe