Applying Constructionist Principles to Online Teacher Professional Development

This report explores the first iteration of a teacher professional development courseletgrounded in constructionist theory and activities. This online teacher professional development(oTPD) courselet provided opportunities for teachers to engage in just-in-time, ongoingTPD within a social networking site for educators. The topic of the oTPD was Roboticsand Hands-on Activities in the Classroom. The courselet was designed for teachers who areinterested in integrating constructionist pedagogies into their practice. Key findings of thefirst delivery of the oTPD courselet point to a need for flexible access, sharing of resources,and support for constructionist pedagogical activities as a PD value for participants. Findingsfurther support the potential for an ongoing online community of practice around roboticsin the classroom. The approach taken in this oTPD courselet of study continues toinform a model of oTPD delivery within a social-networking-enabled environment

GRB Energetics in the Swift Era

We examine the rest frame energetics of 76 gamma-ray bursts (GRBs) with known redshift that were detected by the Swift spacecraft and monitored by the satellite's X-ray Telescope (XRT). Using the bolometric fluence values estimated in Butler et al. 2007b and the last XRT observation for each event, we set a lower limit the their collimation corrected energy Eg and find that a 68% of our sample are at high enough redshift and/or low enough fluence to accommodate a jet break occurring beyond the last XRT observation and still be consistent with the pre-Swift Eg distribution for long GRBs. We find that relatively few of the X-ray light curves for the remaining events show evidence for late-time decay slopes that are consistent with that expected from post jet break emission. The breaks in the X-ray light curves that do exist tend to be shallower and occur earlier than the breaks previously observed in optical light curves, yielding a Eg distribution that is far lower than the pre-Swift distribution. If these early X-ray breaks are not due to jet effects, then a small but significant fraction of our sample have lower limits to their collimation corrected energy that place them well above the pre-Swift Eg distribution. Either scenario would necessitate a much wider post-Swift Eg distribution for long cosmological GRBs compared to the narrow standard energy deduced from pre-Swift observations. We note that almost all of the pre-Swift Eg estimates come from jet breaks detected in the optical whereas our sample is limited entirely to X-ray wavelengths, furthering the suggestion that the assumed achromaticity of jet breaks may not extend to high energies.Comment: 30 pages, 10 figures, Accepted to Ap

Perancangan Mesin Pemotong Kawat Bendrat Di PT. Surabaya Wire

Persaingan ketat di dunia industri seringkali menuntut pengusaha untuk menggunakan proses otomasi agar dapat meningkatkan kinerja mereka. Proses penimbangan dan pemotongan yang ada pada PT. Surabaya Wire masih manual dan membutuhkan waktu yang lama, sehingga dibutuhkan sebuah alat yang dapat memisahkan 1 kg kawat bendrat dan memotongnya secara otomatis. Proses ini dibagi menjadi dua bagian besar yaitu bagian pemisahan 1 kg kawat bendrat dan bagian pemotongan. Konsep dasar untuk memisahkan 1 kg kawat bendrat adalah dengan menggunakan panjangnya sebagai acuan. Ketika panjang kawat bendrat sudah sama dengan 1 kg, maka gulungan kawat akan dipisahkan dan dilanjutkan ke proses pemotongan. Bagian pemotongan menggunakan konsep sebuah tang potong namun lengan pemotong dimodifikasi agar dapat dilewati oleh gulungan kawat yang jatuh dari mesin coiler dan akhirnya dapat dipotong. Simulasi akan dilakukan terlebih dahulu sebelum proses fabrikasi.. Simulasi hanya dilakukan pada bagian pengambilan 1 kg. Simulasi yang dilakukan gagal karena pengambilan kawat tersebut ketika ditimbang terbaca 1.57 kg. Sehingga dibutuhkan penyesuaian lebih lanjut agar rancangan dapat berhasil

Climate adaptation by crop migration.

Many studies have estimated the adverse effects of climate change on crop yields, however, this literature almost universally assumes a constant geographic distribution of crops in the future. Movement of growing areas to limit exposure to adverse climate conditions has been discussed as a theoretical adaptive response but has not previously been quantified or demonstrated at a global scale. Here, we assess how changes in rainfed crop area have already mediated growing season temperature trends for rainfed maize, wheat, rice, and soybean using spatially-explicit climate and crop area data from 1973 to 2012. Our results suggest that the most damaging impacts of warming on rainfed maize, wheat, and rice have been substantially moderated by the migration of these crops over time and the expansion of irrigation. However, continued migration may incur substantial environmental costs and will depend on socio-economic and political factors in addition to land suitability and climate

A Complete Catalog of Swift GRB Spectra and Durations: Demise of a Physical Origin for Pre-Swift High-Energy Correlations

We calculate durations and spectral paramaters for 218 Swift bursts detected by the BAT instrument between and including GRBs 041220 and 070509, including 77 events with measured redshifts. Incorporating prior knowledge into the spectral fits, we are able to measure the characteristic $\nu F_{\nu}$ spectral peak energy $E_{\rm pk,obs}$ and the isotropic equivalent energy $E_{\rm iso}$ (1--$10^4$ keV) for all events. This complete and rather extensive catalog, analyzed with a unified methodology, allows us to address the persistence and origin of high-energy correlations suggested in pre-Swift observations. We find that the $E_{\rm pk,obs}$-$E_{\rm iso}$ correlation is present in the Swift sample; however, the best-fit powerlaw relation is inconsistent with the best-fit pre-Swift relation at >5 sigma significance. Moreover, it has a factor >~ 2 larger intrinsic scatter, after accounting for large errors on $E_{\rm pk,obs}$. A large fraction of the Swift events are hard and subluminous relative to (and inconsistent with) the pre-Swift relation, in agreement with indications from BATSE GRBs without redshift. Moreover, we determine an experimental threshold for the BAT detector and show how the $E_{\rm pk,obs}$--$E_{\rm iso}$ correlation arises artificially due to partial correlation with the threshold. We show that pre-Swift correlations found by Amati et al.(2002), Yonetoku et al. (2004), Firmani et al.(2006) (and independently by others) are likely unrelated to the physical properties of GRBs and are likely useless for tests of cosmology. Also, an explanation of these correlations in terms of a detector threshold provides a natural and quantitative explanation for why short-duration GRBs and events at low redshift tend to be outliers to the correlations.Comment: 25 pages, 9 figures, 2 tables, Accepted to Ap

Inter-similarity between coupled networks

Recent studies have shown that a system composed from several randomly interdependent networks is extremely vulnerable to random failure. However, real interdependent networks are usually not randomly interdependent, rather a pair of dependent nodes are coupled according to some regularity which we coin inter-similarity. For example, we study a system composed from an interdependent world wide port network and a world wide airport network and show that well connected ports tend to couple with well connected airports. We introduce two quantities for measuring the level of inter-similarity between networks (i) Inter degree-degree correlation (IDDC) (ii) Inter-clustering coefficient (ICC). We then show both by simulation models and by analyzing the port-airport system that as the networks become more inter-similar the system becomes significantly more robust to random failure.Comment: 4 pages, 3 figure