MATHEMATICS TEACHER CANDIDATES NOTICE HOW?

The aim of this research is to examine how mathematics teacher candidates' expressions about what they noticed in videos changed with video-clubs. The study group consisted of 5 teacher candidates studying in the 4th grade of Mathematics Education Department. The data of the study, which used focus group interviews that one of the qualitative research methods, consisted of students' notes while watching the videos and focus group interview video recordings. For the analysis of the data, content analysis that is one of the qualitative data analysis methods was used. Changes in the ways in which teacher candidates expressed the situations they noticed during the meetings were examined separately. It has been determined that teacher candidates’ expressions change according to the teacher they see in the video. If the teacher candidates like the teacher on video, they will use a more affirmative language, if they do not like the teacher in the next video, they will suddenly become critical and judgmental. Article visualizations

Method to determine the decolorization potential of persistent dyes by white rot fungi by colorimetric assays

Publisher Copyright: © 2022 The AuthorsDecolorization assays allow to assess the ability of white rot fungi to degrade persistent organic molecules such as textile dyes and can contribute to discover microorganisms that can be used for bioremediation. The decolorization can be overlayed by the absorption from metabolites that are produced by fungi during screening, which interfere with the results. To compensate for this interference a method was developed by using different controls to subtract interfering signals. The method was designed for simple screening in multiwell plates that can be operated with a plate reader. It was applied to four different textile dyes (Reactive Black 5, Reactive Blue 4, Reactive Green 19, and Reactive Orange 16) that were degraded by the white rot fungus Phanerochaete velutina. The four textile dyes showed different results with a different degree of interference. The controls allow to compensate for interfering signals and to calculate kinetic parameters for the decolorization reaction and the enzymatic degradation. • Determine the non-enzymatic degradation of the dyes in experiments without fungi. • Determine the absorbance of metabolites and subtract it from the decolorization data to obtain the degradation of the dye. • Determine kinetic parameters of the degradation to compare the efficiency of the enzymes towards dyes.Peer reviewe

PKS 0537-286, carrying the information of the environment of SMBHs in the early Universe

We present the results of a multifrequency campaign on the high-redshift (z = 3.1) blazar PKS 0537-286. The source was observed at different epochs from 2006 to 2008 with INTEGRAL and Swift, and nearly simultaneously with ground-based near-IR/optical telescopes. The SEDs are compatible with a model based on synchrotron radiation and external inverse Compton scattering. The campaign gives an insight into the physical environment of the blazar.Comment: 8 pages, 5 figures, accepted for publication in A&

The bright optical/NIR afterglow of the faint GRB 080710 - Evidence for a jet viewed off axis

We investigate the optical/near-infrared light curve of the afterglow of GRB 080710 in the context of rising afterglows. Optical and near-infrared photometry was performed using the seven channel imager GROND and the Tautenburg Schmidt telescope. X-ray data were provided by the X-ray Telescope onboard the Swift satellite. The optical/NIR light curve of the afterglow of GRB 080710 is dominated by an initial increase in brightness, which smoothly turns over into a shallow power law decay. The initially rising achromatic light curve of the afterglow of GRB 080710 can be accounted for with a model of a burst viewed off-axis or a single jet in its pre deceleration phase and in an on-axis geometry. An unified picture of the afterglow light curve and prompt emission properties can be obtained with an off-axis geometry, suggesting that late and shallow rising optical light curves of GRB afterglows might be produced by geometric effects.Comment: 9 pages, 4 figures, accepted by A and

The extinction properties of long GRB host galaxies from H and He I recombination lines

In this paper we show how a self-consistent treatment of hydrogen and helium emission line fluxes of the hosts of long gamma-ray bursts can result in improved understanding of the dust properties in these galaxies. In particular, we find that even with modest signal to noise spectroscopy we can differentiate different values for R_V, the ratio of total to selective extinction. The inclusion of Paschen and Brackett lines, even at low signal to noise, greatly increase the accuracy of the derived reddening. This method is often associated with strong systematic errors, caused by the need for multiple instruments to cover the wide wavelength range, the requirement to separate stellar hydrogen absorption from the nebular emission, and because of the dependancy of the predicted line fluxes on the electron temperature. We show how these three systematic errors can be negated, by using suitable instrumentation (in particular X-shooter on the Very Large Telescope) and wide wavelength coverage. We demonstrate this method using an extensive optical and near-infrared spectroscopic campaign of the host galaxy of gamma-ray burst 060218 (SN 2006aj), obtained with FORS1, UVES and ISAAC on the VLT, covering a broad wavelength range with both high and low spectral resolution. We contrast our findings of this source with X-shooter data of a star forming region in the host of GRB 100316D, and show the improvement over existing published fluxes of long GRB hosts.Comment: 10 pages, 7 figures; accepted for publication in MNRA

CHANDRA Detection of 16 New X-Ray Sources

We have detected 18 sources over 6 sigma threshold within two regions 8.3X16.9 arcmin^2 and 8.3X33.6 arcmin^2 in the vicinity of the point with alpha=03h31m02.45s (J2000) and delta=+43degree47arcmin58.5arcsec (J2000) using a CHANDRA ACIS (S+I) observation. Two of the sources were detected before with $ROSAT$ HRI and one source could be closely identified with a star in the optical catalog, USNO A-2. We have also studied source spectra applying four spectral models to the data. Most of the sources can be classified as Cataclysmic Variable, Low Mass X-ray Binary or single star candidates due to their spectral characteristics and luminosities. We also searched for the extragalactic origin for these 18 sources. The source count rates vary between 5.8X10^{-4}- 4.7X10^{-3} counts/s. Due to low count rates temporal characteristics of the sources can not be studied effectively.Comment: 7 pages, 1 figures, accepted to Astronomy and Astrophysic

The missing gas problem in GRB host galaxies: evidence for a highly ionised component

There is considerable discrepancy between the amount of X-ray absorption and that inferred from optical (rest frame UV) as measured along gamma-ray burst (GRB) sight lines, with the former being typically an order of magnitude higher than what would be expected from the measurement of neutral element species via optical absorption line spectroscopy. We explore this "missing gas problem" by using X-ray and optical measurements in a sample of 29 z=0.7-6.3 GRBs from both spectroscopic data and the afterglow broadband spectral energy distributions. The low ionisation species detected in the UV are associated with the neutral interstellar medium in the GRB host galaxy, while soft X-ray absorption, which is weakly dependent on the ionisation state of the gas, provides a probe of the total column of gas along the sight line. After careful consideration of any systematic effects, we find that the neutral gas consists of less than ~10% of the total gas, and this limit decreases with the more ionised that the X-ray absorbing gas is, which in our spectral fits is assumed to be neutral. Only a very small fraction of this ionised gas, however, is detected in UV absorption lines with ionisation potentials up to ~200eV (i.e. SiIV, CIV, NV, OVI), which leaves us to postulate that the X-ray excess is due to ultra-highly-ionised, dense gas in the GRB vicinity.Comment: 10 pages, 4 figures, accepted for publication in A&

A strong optical flare before the rising afterglow of GRB 080129

We report on GROND observations of a 40 sec duration (rest-frame) optical flare from GRB 080129 at redshift 4.349. The rise- and decay time follow a power law with indices +12 and -8, respectively, inconsistent with a reverse shock and a factor 10$^5$ faster than variability caused by ISM interaction. While optical flares have been seen in the past (e.g. GRB 990123, 041219B, 060111B and 080319B), for the first time, our observations not only resolve the optical flare into sub-components, but also provide a spectral energy distribution from the optical to the near-infrared once every minute. The delay of the flare relative to the GRB, its spectral energy distribution as well as the ratio of pulse widths suggest it to arise from residual collisions in GRB outflows \cite{liw08}.If this interpretation is correct and can be supported by more detailed modelling or observation in further GRBs, the delay measurement provides an independent, determination of the Lorentz factor of the outflow.Comment: accepted for publ. in ApJ, 5 Fig

Evidence for Supernova-Synthesised Dust from the Rising Afterglow of GRB 071025 at z~5

We present observations and analysis of the broadband afterglow of Swift GRB 071025. Using optical and infrared (RIYJHK) photometry, we derive a photometric redshift of 4.4 < z < 5.2; at this redshift our simultaneous multicolour observations begin at ~30 s after the GRB trigger in the host frame and during the initial rising phase of the afterglow. We associate the light curve peak at 580 s in the observer frame with the formation of the forward shock, giving an estimate of the initial Lorentz factor Gamma_0 ~ 200. The red spectral energy distribution (even in regions not affected by the Lyman-alpha break) provides secure evidence of a large dust column. However, the inferred extinction curve shows a prominent flat component between 2000-3000 Angstroms in the rest-frame, inconsistent with any locally observed template but well-fit by models of dust formed by supernovae. Time-dependent fits to the extinction profile reveal no evidence of dust destruction and limit the decrease in the extinction column to Delta A_3000 < 0.54 mag after t = 50 s in the rest frame. Our observations provide evidence of a transition in dust properties at z~5, in agreement with studies of high-z quasars, and suggest that SN-formed dust continues to dominate the opacity of typical galaxies at this redshift.Comment: Resubmitted to MNRAS following referee report. Contains additional figure and some extra analysis/discussio