Formação continuada de professores de ciências para o ensino de astronomia nos anos iniciais do ensino fundamental

Situated at the intersection of Continuing Formation, Science Teaching and content of astronomy, the research aims to discuss this problematic : What are the challenges encountered in a continuous formation in service of science teachers of the early years of elementary school with contents of astronomy? Aiming to answer this question, we carried out a collaborative action research in a school of Natal / RN, with 6 teachers who teach or lectured Natural Sciences in the early years of elementary school. The study involved 14 encounters of continuos formation in service, to enable a better understanding criticism and propositive concerning the teaching science, especially some content of astronomy for the initial years, through a shared discussion. To this end, we consider that more profound understanding of astronomical knowledge allows the establishment of relationships and connections between theoretical knowledge and the daily teaching practice. All discussions were recorded on audio and transcripts. This research was realized using questionnaires and diary, however, the audio recording was its principal working instrument. About the data collected, several issues emerged as the little field of conceptual content, several misconceptions among teachers about the content of astronomy, lack of adequate space in the school environment to study and the need for collective reflection on the practice. Finally, is indicated that the contents of astronomy should be used in classrooms of Sciences, provided that teaching plan of action consider the existence of diverse alternative conceptions about the subject, among both teachers and students, and the need of permanente continuing education in the teaching

The Journal of science, and annals of astronomy, biology, geology, industrial arts, manufactures, and technology

Vols. 8-15 also called New Series, vols. 1-8; vols. 16-22, also called 3d. series, vols. 1-7

THE STELLAR CONTENT OF OBSCURED GALACTIC GIANT H II REGIONS. VII. W3

Spectrophotometric distances in the K band have been reported by different authors for a number of obscured Galactic H II regions. Almost 50% of them show large discrepancies compared to the classical method using radial velocities measured in the radio spectral region. In order to provide a crucial test of both methods, we selected a target that does not present particular difficulty for any method and which has been measured by as many techniques as possible. The W3 star-forming complex, located in the Perseus arm, offers a splendid opportunity for such a task. We used the Near-Infrared Integral Field Spectrograph on the Frederick C. Gillett Gemini North telescope to classify candidate ""naked photosphere"" OB stars based on Two Micron All Sky Survey photometry. Two of the targets are revealed to be mid-O-type main-sequence stars leading to a distance of d = 2.20 kpc. This is in excellent agreement with the spectrophotometric distance derived in the optical band (d = 2.18 pc) and with a measurement of the W3 trigonometric parallax (d = 1.95 kpc). Such results confirm that the spectrophotometric distances in the K band are reliable. The radio-derived kinematic distance, on the contrary, gives a distance twice as large (d = 4.2 kpc). This indicates that this region of the Perseus arm does not follow the Galactic rotation curve, and this may also be the case for other H II regions for which discrepancies have been found.

The metal content of bulge field stars from FLAMES-GIRAFFE spectra - I. Stellar parameters and iron abundances

Aims. We determine the iron distribution function (IDF) for bulge field stars, in three different fields along the Galactic minor axis and at latitudes b = -4 degrees, b = -6 degrees, and b = -12 degrees. A fourth field including NGC 6553 is also included in the discussion. Methods. About 800 bulge field K giants were observed with the GIRAFFE spectrograph of FLAMES@VLT at spectral resolution R similar to 20 000. Several of them were observed again with UVES at R similar to 45 000 to insure the accuracy of the measurements. The LTE abundance analysis yielded stellar parameters and iron abundances that allowed us to construct an IDF for the bulge that, for the first time, is based on high-resolution spectroscopy for each individual star. Results. The IDF derived here is centered on solar metallicity, and extends from [Fe/H] similar to -1.5 to [Fe/H] similar to + 0.5. The distribution is asymmetric, with a sharper cutoff on the high-metallicity side, and it is narrower than previously measured. A variation in the mean metallicity along the bulge minor axis is clearly between b = -4 degrees and b = -6 degrees ([Fe/H] decreasing similar to by 0.6 dex per kpc). The field at b = -12 degrees. is consistent with the presence of a gradient, but its quantification is complicated by the higher disk/bulge fraction in this field. Conclusions. Our findings support a scenario in which both infall and outflow were important during the bulge formation, and then suggest the presence of a radial gradient, which poses some challenges to the scenario in which the bulge would result solely from the vertical heating of the bar.

The stellar content of obscured Galactic giant H II regions. VI. W51A

We present K-band spectra of newly born OB stars in the obscured Galactic giant H II region W51A and approximate to 0.8 '' angular resolution images in the J, H, and K(S)-bands. Four objects have been spectroscopically classified as O-type stars. The mean spectroscopic parallax of the four stars gives a distance of 2.0 +/- 0.3 kpc (error in the mean), significantly smaller than the radio recombination line kinematic value of 5.5 kpc or the values derived from maser proper motion observations (6-8 kpc). The number of Lyman continuum photons from the contribution of all massive stars (NLyc approximate to 1.5 x 10(50) s(-1)) is in good agreement with that inferred from radio recombination lines (NLyc = 1.3 x 10(50) s(-1)) after accounting for the smaller distance derived here. We present analysis of archival high angular resolution images (NAOS CONICA at VLT and T-ReCS at Gemini) of the compact region W51 IRS 2. The K(S)-band images resolve the infrared source IRS 2 indicating that it is a very young compact H II region. Sources IRS 2E was resolved into compact cluster (within 660 AU of projected distance) of three objects, but one of them is just bright extended emission. W51d1 and W51d2 were identified with compact clusters of three objects (maybe four in the case of W51d1) each one. Although IRS 2E is the brightest source in the K-band and at 12.6 mu m, it is not clearly associated with a radio continuum source. Our spectrum of IRS 2E shows, similar to previous work, strong emission in Br gamma and He I, as well as three forbidden emission lines of Fe III and emission lines of molecular hydrogen (H(2)) marking it as a massive young stellar object.

Characterization and Application of Educational Virtual Environments for Science Teaching in Secondary School

This work describes the characteristics of a representative set of seven different virtual laboratories (VLs) aimed for science teaching in secondary school. For this purpose, a 27-item evaluation model that facilitates the characterization of the VLs was prepared. The model takes into account the gaming features, the overall usability, and also the potential to induce scientific literacy. Five of the seven VLs were then tested with two larger and highly heterogenic groups of students, and in two different contexts – biotechnology and physics, respectively. It is described how the VLs were received by the students, taking into account both their motivation and their self-reported learning outcome. In some cases, students’ approach to work with the VLs was recorded digitally, and analyzed qualitatively. In general, the students enjoyed the VL activities, and claimed that they learned from them. Yet, more investigation is required to address the effectiveness of these tools for significant learning.

Thinking Outside the Box: Enhancing Science Teaching by Combining (Instead of Contrasting) Laboratory and Simulation Activities

The focus of the present work was on 10- to 12-year-old elementary school students’ conceptual learning outcomes in science in two specific inquiry-learning environments, laboratory and simulation. The main aim was to examine if it would be more beneficial to combine than contrast simulation and laboratory activities in science teaching. It was argued that the status quo where laboratories and simulations are seen as alternative or competing methods in science teaching is hardly an optimal solution to promote students’ learning and understanding in various science domains. It was hypothesized that it would make more sense and be more productive to combine laboratories and simulations. Several explanations and examples were provided to back up the hypothesis. In order to test whether learning with the combination of laboratory and simulation activities can result in better conceptual understanding in science than learning with laboratory or simulation activities alone, two experiments were conducted in the domain of electricity. In these experiments students constructed and studied electrical circuits in three different learning environments: laboratory (real circuits), simulation (virtual circuits), and simulation-laboratory combination (real and virtual circuits were used simultaneously). In order to measure and compare how these environments affected students’ conceptual understanding of circuits, a subject knowledge assessment questionnaire was administered before and after the experimentation. The results of the experiments were presented in four empirical studies. Three of the studies focused on learning outcomes between the conditions and one on learning processes. Study I analyzed learning outcomes from experiment I. The aim of the study was to investigate if it would be more beneficial to combine simulation and laboratory activities than to use them separately in teaching the concepts of simple electricity. Matched-trios were created based on the pre-test results of 66 elementary school students and divided randomly into a laboratory (real circuits), simulation (virtual circuits) and simulation-laboratory combination (real and virtual circuits simultaneously) conditions. In each condition students had 90 minutes to construct and study various circuits. The results showed that studying electrical circuits in the simulation–laboratory combination environment improved students’ conceptual understanding more than studying circuits in simulation and laboratory environments alone. Although there were no statistical differences between simulation and laboratory environments, the learning effect was more pronounced in the simulation condition where the students made clear progress during the intervention, whereas in the laboratory condition students’ conceptual understanding remained at an elementary level after the intervention. Study II analyzed learning outcomes from experiment II. The aim of the study was to investigate if and how learning outcomes in simulation and simulation-laboratory combination environments are mediated by implicit (only procedural guidance) and explicit (more structure and guidance for the discovery process) instruction in the context of simple DC circuits. Matched-quartets were created based on the pre-test results of 50 elementary school students and divided randomly into a simulation implicit (SI), simulation explicit (SE), combination implicit (CI) and combination explicit (CE) conditions. The results showed that when the students were working with the simulation alone, they were able to gain significantly greater amount of subject knowledge when they received metacognitive support (explicit instruction; SE) for the discovery process than when they received only procedural guidance (implicit instruction: SI). However, this additional scaffolding was not enough to reach the level of the students in the combination environment (CI and CE). A surprising finding in Study II was that instructional support had a different effect in the combination environment than in the simulation environment. In the combination environment explicit instruction (CE) did not seem to elicit much additional gain for students’ understanding of electric circuits compared to implicit instruction (CI). Instead, explicit instruction slowed down the inquiry process substantially in the combination environment. Study III analyzed from video data learning processes of those 50 students that participated in experiment II (cf. Study II above). The focus was on three specific learning processes: cognitive conflicts, self-explanations, and analogical encodings. The aim of the study was to find out possible explanations for the success of the combination condition in Experiments I and II. The video data provided clear evidence about the benefits of studying with the real and virtual circuits simultaneously (the combination conditions). Mostly the representations complemented each other, that is, one representation helped students to interpret and understand the outcomes they received from the other representation. However, there were also instances in which analogical encoding took place, that is, situations in which the slightly discrepant results between the representations ‘forced’ students to focus on those features that could be generalised across the two representations. No statistical differences were found in the amount of experienced cognitive conflicts and self-explanations between simulation and combination conditions, though in self-explanations there was a nascent trend in favour of the combination. There was also a clear tendency suggesting that explicit guidance increased the amount of self-explanations. Overall, the amount of cognitive conflicts and self-explanations was very low. The aim of the Study IV was twofold: the main aim was to provide an aggregated overview of the learning outcomes of experiments I and II; the secondary aim was to explore the relationship between the learning environments and students’ prior domain knowledge (low and high) in the experiments. Aggregated results of experiments I & II showed that on average, 91% of the students in the combination environment scored above the average of the laboratory environment, and 76% of them scored also above the average of the simulation environment. Seventy percent of the students in the simulation environment scored above the average of the laboratory environment. The results further showed that overall students seemed to benefit from combining simulations and laboratories regardless of their level of prior knowledge, that is, students with either low or high prior knowledge who studied circuits in the combination environment outperformed their counterparts who studied in the laboratory or simulation environment alone. The effect seemed to be slightly bigger among the students with low prior knowledge. However, more detailed inspection of the results showed that there were considerable differences between the experiments regarding how students with low and high prior knowledge benefitted from the combination: in Experiment I, especially students with low prior knowledge benefitted from the combination as compared to those students that used only the simulation, whereas in Experiment II, only students with high prior knowledge seemed to benefit from the combination relative to the simulation group. Regarding the differences between simulation and laboratory groups, the benefits of using a simulation seemed to be slightly higher among students with high prior knowledge. The results of the four empirical studies support the hypothesis concerning the benefits of using simulation along with laboratory activities to promote students’ conceptual understanding of electricity. It can be concluded that when teaching students about electricity, the students can gain better understanding when they have an opportunity to use the simulation and the real circuits in parallel than if they have only the real circuits or only a computer simulation available, even when the use of the simulation is supported with the explicit instruction. The outcomes of the empirical studies can be considered as the first unambiguous evidence on the (additional) benefits of combining laboratory and simulation activities in science education as compared to learning with laboratories and simulations alone.

Particle size and cholesterol content of a mayonnaise formulated by OSA-modified potato starch

Egg yolk was partially replaced (0, 25, 50, 75, and 100%) with octenyl succinic anhydride (OSA)-modified potato starch in a reduced-fat mayonnaise formulation to curtail the problems associated with high cholesterol and induced allergic reactions. The physicochemical properties included parameters such as: pH, fat content, and emulsion stability of the formulations analyzed. The samples with 75% and 100% egg yolk substitute showed the maximum emulsion stability (>95% after two of months storage), and they were selected according to cholesterol content, particle size distributions, dynamic rheological properties, microstructure, and sensory characteristic. A significant reduction (84-97%) in the cholesterol content was observed in the selected samples. Particle size analysis showed that by increasing the amount of OSA starch, the oil droplets with the peak size of 70 µm engulfed by this compound became larger. The rheological tests elucidated that in the absence of egg yolk, OSA starch may not result in a final product with consistent texture and that the best ratio of the two emulsifiers (OSA starch/egg yolk) to produce stable reduced-fat, low cholesterol mayonnaise is 75/25. The microscopic images confirmed the formation of a stable cohesive layer of starch surrounding the oil droplets emulsified in the samples selected.

The effects of low-temperature potato storage and washing and soaking pre-treatments on the acrylamide content of French fries

BACKGROUND: Since the discovery in 2002 of acrylamide in a wide range of foods, there has been much work done to explore mechanisms of formation and to reduce acrylamide in commercial products. This study aimed to investigate simple measures which could be used to reduce acrylamide formation in home-cooked French fries, using potatoes from three cultivars stored under controlled conditions and sampled at three time points. RESULTS: The reducing sugar content for all three cultivars increased during storage, which led to increased acrylamide levels in the French fries. Washing and soaking (30 min or 2 h) raw French fries before cooking led to reductions in acrylamide of up to 23, 38 and 48% respectively. Pre-treated fries were lighter in colour after cooking than the corresponding controls. CONCLUSION: Pre-treatments such as soaking or washing raw French fries in water reduce acrylamide and colour formation in the final product when cooking is stopped at a texture-determined endpoint. (c) 2008 Society of Chemical Industry.

Random primordial magnetic fields and the gas content of dark matter haloes

We recently predicted the existence of random primordial magnetic fields (RPMFs) in the form of randomly oriented cells with dipole-like structure with a cell size L(0) and an average magnetic field B(0). Here, we investigate models for primordial magnetic field with a similar web-like structure, and other geometries, differing perhaps in L(0) and B(0). The effect of RPMF on the formation of the first galaxies is investigated. The filtering mass, M(F), is the halo mass below which baryon accretion is severely depressed. We show that these RPMF could influence the formation of galaxies by altering the filtering mass and the baryon gas fraction of a halo, f(g). The effect is particularly strong in small galaxies. We find, for example, for a comoving B(0) = 0.1 mu G, and a reionization epoch that starts at z(s) = 11 and ends at z(e) = 8, for L(0) = 100 pc at z = 12, the f(g) becomes severely depressed for M < 10(7) M(circle dot), whereas for B(0) = 0 the f(g) becomes severely depressed only for much smaller masses, M < 10(5) M(circle dot). We suggest that the observation of M(F) and f(g) at high redshifts can give information on the intensity and structure of primordial magnetic fields.

Evaluating microfossil content of dental calculus from Brazilian sambaquis

To date, limited numbers of dental calculus samples have been analyzed by researchers in diverse parts of the world. The combined analyses of these have provided some general guidelines for the analysis of calculus that is non-destructive to archaeological teeth. There is still a need for a quantitative study of large numbers of calculus samples to establish protocols, assess the level of contamination, evaluate the quantity of microfossils in dental calculus, and to compare analysis results with the literature concerning the biology of calculus formation. We analyzed dental calculus from 53 teeth from four Brazilian sambaquis. Sambaquis are the shell-mounds that were established prehistorically along the Brazilian coast. The analysis of sambaqui dental calculi shows that there are relatively high concentrations of microfossils (phytoliths and starch), mineral fragments, and charcoal in dental calculus. Mineral fragments and charcoal are possibly contaminants. The largest dental calculi have the lowest concentrations of microfossils. Biologically, this is explained by individual variation in calculus formation between people. Importantly, starch is ubiquitous in dental calculus. The starch and phytoliths show that certainly Dioscorea (yam) and Araucaria angustifolia (Parana pine) were eaten by sambaqui people. Araceae (arum family), Ipomoea batatas (sweet potato) and Zea mays (maize) were probably in their diet. (C) 2009 Elsevier Ltd. All rights reserved.

Nothing too much: reflecting about the role of contextualization in science teaching

The contextualization and discussion about the science role in the social and economical development are unquestionably important for the science teaching process. It doesn't mean, however, that the scientific-theoretic knowledge and the strategies involved in its construction and application might be neglected. In this way, a dangerous situation is created when the contextualization is assumed as a unique and primordial target in science education. This paper presents a research carried out with 15 future chemistry teachers and the results show a worrying "supervalorization", of the contextualization beside other equally important aspects of the chemical knowledge.

The globular cluster kinematics and galaxy dark matter content of NGC 3923

This paper presents further results from our spectroscopic study of the globular cluster (GC) system of the group elliptical NGC 3923. From observations made with the GMOS instrument on the Gemini South Telescope, an additional 50 GC and ultra-compact dwarf (UCD) candidates have been spectroscopically confirmed as members of the NGC 3923 system. When the recessional velocities of these GCs are combined with the 29 GC velocities reported previously, a total sample of 79 GC/UCD velocities is produced. This sample extends to over 6 arcmin (>6 R-e similar to 30 kpc) from the centre of NGC 3923 and is used to study the dynamics of the GC system and the dark matter content of NGC 3923. It is found that the GC system of NGC 3923 displays no appreciable rotation, and that the projected velocity dispersion is constant with radius within the uncertainties. The velocity dispersion profiles of the integrated light and GC system of NGC 3923 are indistinguishable over the region in which they overlap. We find some evidence that the diffuse light and GCs of NGC 3923 have radially biased orbits within similar to 130 arcsec. The application of axisymmetric orbit-based models to the GC and integrated light velocity dispersion profiles demonstrates that a significant increase in the mass-to-light ratio (from M/L-V = 8 to 26) at large galactocentric radii is required to explain this observation. We therefore confirm the presence of a dark matter halo in NGC 3923. We find that dark matter comprises 17.5(-4.5)(+7.3) per cent of the mass within 1 R-e, 41.2(-10.6)(+18.2) per cent within 2 R-e and 75.6(-16.8)(+15.4) per cent within the radius of our last kinematic tracer at 6.9 R-e. The total dynamical mass within this radius is found to be 1.5(-0.25)(+0.4) x 10(12) M-circle dot. In common with other studies of large ellipticals, we find that our derived dynamical mass profile is consistently higher than that derived by X-ray observations, by a factor of around 2.

Physico-chemical characteristics and ikaite content of brine and ice samples taken during SIPEX and DDU campaigns in East Antarctica, 2007

Calcium carbonate precipitation in sea ice is thought to potentially drive significant CO2 uptake by the ocean. However, little is known about the quantitative spatial and temporal distribution of CaCO3 within sea ice, although it is hypothesized that high quantities of dissolved organic matter and/or phosphate (common in sea ice) may inhibit its formation. In this quantitative study of hydrous calcium carbonate as ikaite, sea ice cores and brine samples were collected from pack and land fast sea ice between September and December 2007 during two expeditions, one in the East Antarctic sector and the other off Terre Adélie. Samples were analysed for CaCO3, salinity, dissolved organic carbon/nitrogen, inorganic phosphate, and total alkalinity. No relationship between these parameters and CaCO3 precipitation was evident. Ikaite was found mostly in the uppermost layers of sea ice with maximum concentrations of up to 126 mg ikaite per litre melted sea ice being measured, although both the temporal and horizontal spatial distributions of ikaite were highly heterogeneous. The precipitate was also found in the snow on top of the sea ice at some of the sampling locations.