An Exploratory Study of the Impact of an Inquiry-Based Professional Development Course on the Beliefs and Instructional Practices of Urban Inservice Teachers

Five urban teachers completed a total of 50 contact hours, over a seven month period, of professional development, in which they: participated in authentic, inquiry based experiences facilitated by a scientist; learned new science content related to the nature of science and scientific inquiry; developed inquiry-based lesson plans to implement in their classrooms; and developed science-specific strategies to mentor novice and experienced teachers. The focus of this research was to determine changes in their: beliefs and instructional practices; understanding of scientific literacy; and efficacy toward mentoring other teachers. A collective case study methodology was used in which participants completed questionnaires and were observed and interviewed, prior to and at the completion of the course. They were also asked to complete reflective journal questions during the course. While the teachers\u27 beliefs did not change as measured by the Teacher\u27s Pedagogical Philosophy Interview (TPPI) (teacher-centered beliefs for Teacher Actions and Teacher and Content ; conceptual/student-centered for Student Actions and Philosophy of Teaching ), their teacher-centered behaviors changed to conceptual/student-centered as measured by the Secondary Science Teachers Analysis Matrix (STAM). Their responses to the Constructivist Learning Environment Survey (CLES) generally correlated with their post-STAM results. Participants gained a better understanding of the creative aspect of the nature of science as measured by the Modified Nature of Scientific Knowledge Scale (MNSKS) instrument, while two novice teachers improved their personal science teaching efficacy after participation in the course as measured by the Science Teaching Efficacy Belief Instrument (STEBI). Four of the five teachers felt better prepared to mentor others to use inquiry-based instruction. In contrast to these positive trends, their outcome expectancy beliefs (STEBI subscale) were generally lower than their perceived personal teaching efficacy before and after the course, which could be an indicator of the environment in urban schools where there is often little support or equipment for innovative practices in science. Generally there was a shift from traditional to constructivist instructional practices as measured by the STAM, while results varied for teacher beliefs and efficacy regarding science instruction as measured by the TPPI, CLES, and STEBI and teachers’ understanding of the nature of science as measured by the MNSKS

Crown Reductions and Decompositions: Theoretical Results and Practical Methods

Two kernelization schemes for the vertex cover problem, an NP-hard problem in graph theory, are compared. The first, crown reduction, is based on the identification of a graph structure called a crown and is relatively new while the second, LP-kernelization has been used for some time. A proof of the crown reduction algorithm is presented, the algorithm is implemented and theorems are proven concerning its performance. Experiments are conducted comparing the performance of crown reduction and LP- kernelization on real world biological graphs. Next, theorems are presented that provide a logical connection between the crown structure and LP-kernelization. Finally, an algorithm is developed for decomposing a graph into two subgraphs: one that is a crown and one that is crown free

Radio and X-ray variability of Young Stellar Objects in the Coronet Cluster

The Coronet Cluster in the nearby R CrA dark cloud offers the rare opportunity to study at least four "class I" protostellar sources as well as one candidate "class 0" source, a Herbig Ae star, and a candidate brown dwarf within a few square arcminutes - most of them detected at radio- and X-ray wavelengths. These sources were observed with the Very Large Array (VLA) at 3.5cm on nine occasions in 1998, spread over nearly four months. The source IRS 5, earlier shown to emit circularly polarized radio emission, was observed to undergo a flux increase accompanied by changes in its polarization properties. Comparison with VLA measurements taken in January 1997 allows for some analysis of longer-term variability. In addition to this radio monitoring, we analyze archival Chandra and XMM-Newton X-ray data of these sources. Three class I protostars are bright enough for X-ray spectroscopy, and we perform a variability analysis for these sources, covering a total of 154 ksec spread over more than two and a half years. Also in X-rays, IRS 5 shows the most pronounced variability, whilst the other two class I protostars IRS 1 and IRS 2 have more stable emission. X-ray data is also analyzed for the recently identified candidate class 0 source IRS 7E, which shows strong variability as well as for the Herbig Ae star R CrA for which we find extremely hot X-ray-emitting plasma. For IRS 1,2 and 5, the hydrogen column densities derived from the X-ray spectra are at about half the values derived with near-infrared techniques, a situation similar to what has been observed towards some other young stellar objects.Comment: 17 pages, 11 figures, accepted for publication in A&

The prestellar and protostellar population of R Coronae Australis

We present 450 and 850 um maps of R Coronae Australis. We compare the maps to previous surveys of the region, and shed new light on the previously unknown nature of the protostellar sources at the centre of the cloud. We clarify the nature of two millimetre sources previously discovered in lower resolution data. We identify one new Class 0 protostar that we label SMM 1B, and we measure the envelope masses of a number of more evolved protostars. We identify two new prestellar cores that we call SMM 1A and SMM 6.Comment: 8 page

Finding Maximal Common Subgraphs via Time-Space Efficient Reverse Search

International audienceFor any two given graphs, we study the problem of finding isomorphisms that correspond to inclusion-maximal common induced subgraphs that are connected. While common (induced or not) subgraphs can be easily listed using some well known reduction and state-of-the-art algorithms, they are not guaranteed to be connected. To meet the connectivity requirement, we propose an algorithm that revisits the paradigm of reverse search and guarantees polynomial time per solution (delay) and linear space, on top of showing good practical performance

On Maximum Weight Clique Algorithms, and How They Are Evaluated

Maximum weight clique and maximum weight independent set solvers are often benchmarked using maximum clique problem instances, with weights allocated to vertices by taking the vertex number mod 200 plus 1. For constraint programming approaches, this rule has clear implications, favouring weight-based rather than degree-based heuristics. We show that similar implications hold for dedicated algorithms, and that additionally, weight distributions affect whether certain inference rules are cost-effective. We look at other families of benchmark instances for the maximum weight clique problem, coming from winner determination problems, graph colouring, and error-correcting codes, and introduce two new families of instances, based upon kidney exchange and the Research Excellence Framework. In each case the weights carry much more interesting structure, and do not in any way resemble the 200 rule. We make these instances available in the hopes of improving the quality of future experiments

The unnatural act of management: when the great leader's work is done, the people say, "we did it ourselves"

Arguing that managing goes against what is natural the writer demonstrates all the problems facing today's managers, using specific case studies that teach readers how to make decisions, hire the right people, and mor

Near and far infrared observations of protostars and dark clouds

Far infrared point source and extended emission data from the Infrared Astronomical Satellite (IRAS) survey are used to investigate the properties of star formation in the regions of high galactic latitude dark cloud complexes. The properties of individual sources are examined using near infrared spectroscopy and broad band spectral energy distributions. The IRAS signature of star formation is derived by comparing the far infrared colours of a sample of protostars with those of other common far infrared objects. The quality of the IRAS data is ignored for the purposes of this investigation. The criteria developed for identifying protostars from the IRAS Point Source Catalog discriminates against most non-protostellar objects, with the exception of galaxies and Hfl regions. Objects identified as protostellar according to other criteria are also likely to be identified by the criteria developed. Extended emission data in the far infrared is used to estimate the column density and temperature of several dark cloud complexes, and the optical extinction in the same regions is estimated with the Guide Star Catalog. Temperature and column density share an inverse relationship: cloud cores are characterised by column densities above 1024 hydrogen atoms m-2 and temperatures around 20 K, while the inter cloud medium has column densities below 1023 atoms m-2 and temperatures above 50 K. The column density, as measured by IRAS, and the optical extinction appear to be related up to values of around 1025 atoms m-2 and 5 magnitudes respectively, but the IRAS detectors appear insensitive to material at higher densities than these. Near infrared spectra of a variety of objects chosen for their youth, including IRAS sources which satisfy the protostar criteria, are investigated. These spectra are categorised into three distinct groups of increasing youth: 1. T Tauri-like spectra, with flat H and K band continua, lacking both Br-γ emission and CO absorption; 2. FU Ori-like spectra, with CO absorption, 1.9 μm water absorption, and possibly Br-γ emission, and 3. embedded protostar spectra, with red continuum, and perhaps Br-γ emission, but lacking CO absorption. The spectral energy distributions (SEDs) of the sources are also investigated, using data at wavelengths from 0.3 μm to 100 μm. All of the objects studied in the near infrared have SEDs characteristic of either T Tauri stars or of embedded protostars. There seems little correlation between the evolutionary status assigned to an object on the basis of its SED and that assigned from near infrared spectral features, perhaps because the shape of the SED is independent of the evolution of the central object, and depends on geometric considerations such as the orientation of the circumstellar disk in relation to the line of sight from the Earth

A Numerical and Analytical Study of Vortex Rings With Swirl

We study the growth of disturbances to vortex rings with swirl, which are exact solutions of the Euler equations of inviscid flow, using two contrasting methods. The motion of the perturbed vortex rings can be regarded as a prototype for the inviscid dynamics of vortex structures in 3D. Exact rings with swirl are computed as steady, axisymmetric flows using a variational method. Asymptotic analysis in the short wave limit, similar to geometric optics, leads to ordinary differential equations for perturbations along particle paths. These ODE's can be solved for the rings of interest, yielding predicted maximum growth rates for small disturbances. These rates are compared with the direct simulation of sample disturbances using a 3D vortex method to calculate the evolution according to the Euler equations. 1 Introduction In recent years there has been considerable interest in understanding the dynamics of flows with localized vortex structures such as filaments and rings. Despite conside..