The rapid decline of the prompt emission in Gamma-Ray Bursts

Many gamma ray bursts (GRBs) have been observed with the Burst-Alert and X-Ray telescopes of the Swift satellite. The successive `pulses' of these GRBs end with a fast decline and a fast spectral softening, until they are overtaken by another pulse, or the last pulse's decline is overtaken by a less rapidly-varying `afterglow'. The fast decline-phase has been attributed, in the currently-explored standard fireball model of GRBs, to `high-latitude' synchrotron emission from a collision of two conical shells. This high latitude emission does not explain the observed spectral softening. In contrast, the temporal behaviour and the spectral evolution during the fast-decline phase agree with the predictions of the cannonball model of GRBs.Comment: Four added figures comparing the evolution of the inferred effective photon spectral index during the fast decline phase of the prompt emission in 14 selected Swift GRBS and the cannonball (CB) model predictio

Transient-mediated fate determination in a transcriptional circuit of HIV

Steady-state behavior and bistability have been proposed as mechanisms for decision-making in gene circuits. However, transient gene expression has also been proposed to control cell fate with the decision arbitrated by the lifetime of the expression transient. Here, we report that transcriptional positive-feedback plays a critical role in determining HIV infected cell-fate by extending the duration of Tat expression transients far beyond what protein half-life modulation can achieve. To directly quantify feedback strength and its effects on the duration of Tat transcriptional pulses, we exploit the noise inherent to gene-expression and measure shifts in the autocorrelation of expression noise. The results indicate that transcriptional positive-feedback extends the single-cell Tat expression lifetime by ~6-fold for both minimal Tat circuits and full-length, actively-replicating HIV-1. Importantly, artificial weakening of Tat positive-feedback shortened the duration of Tat expression transients and biased the probability in favor of latency. Thus, transcriptional positive-feedback appears to modulate transient expression lifetime and thereby control cell-fate in HIV

Upaya Meningkatkan Hasil Belajar Siswa Dalam Penguasaan Materi Pelajaran Narrative Text Pada Pelajaran Bahasa Inggris Melalui Penerapan Model Pembelajaran Kooperatif Tipe Jigsaw Di Kelas Viii-d SMP Negeri 3 Medan

 Penelitian ini dilatarbelakangi permasalahan yang muncul di SMP Negeri 3 Medan yaitu setelah guru melaksanakan pembelajaran Bahasa Inggris pada materi Narrative text guru mengetahui bahwa hasil belajar masih rendah. Hal ini tercermin dari perolehan tes hasil belajar yaitu bahwa tidak ada siswa yang mencapai ketuntasan individual. Ini juga menunjukkan bahwa belum tercapai standar ketuntasan klasikal karena prosentase ketuntasan adalah sebesar 0%. Dalam proses pembelajaran keaktifan siswalah yang seharusnya ditingkatkan karena proses belajar bukanlah menyampaikan materi tapi bagaimana siswa dapat memperoleh informasi dengan cara-cara mereka sendiri maupun bimbingan guru. Selain itu dalam pembelajaran, ketertarikan siswa atau respon siswa juga sangat mempengaruhi perolehan hasil belajar. Dengan menyadari berbagai Kenyataan diatas maka sebagai seorang guru professional merasa perlu untuk memperbaiki pembelajaran yaitu dengan mengadakan penelitian. Penelitian ini merupakan penelitian tindakan kelas dengan meningkatkan pembelajaran Bahasa Inggris untuk meningkatkan hasil belajar siswa Kelas VIII-D SMP Negeri 3 Medan. Penelitian ini merupakan penelitian tindakan kelas yang dilakukan sebanyak dua siklus. Berdasarkan analisis data dalam penelitian ini bahwa penerapan metode Jigsawdapat meningkatkan kemampuan individual siswa dan ketuntasan klasikal siswa. Penerapan Model Pembelajaran Jigsaw juga dapat membuat siswa lebih aktif. Siswa merespon positif terhadap pembelajaran dengan menerapkan Model Pembelajaran Jigsaw. Model Pembelajaran Jigsawdapat meningkatkan Hasil Belajar Narrative text  siswa Kelas VIII-DSMP Negeri 3 Medan, yaitu nilai rata-rata kelas pada saat pre test 47,537,44; siklus 1: 70,26; siklus 2: 81,79. Model pembelajaran kooperatif tipe Jigsaw dapat menciptakan suasana pembelajaran yang efektif, dan siswa aktif bekerja sama, hal ini ditunjukkan pada nilai sikap siswa pada siklus 1: 45,95; meningkat pada siklus 2: 80,62

Effectiveness of lending for vocational education and training: lessons from World Bank experience

This paper reviews the Bank involvement in the vocational education and training (VET) sub-sector in the 1990s. The paper aims to do just that, by mainly seeking answers to the following questions: 1) How has the Bank performed in its lending services to its clients in VET? 2) How have VET projects performed in terms of meeting stated objectives? 3) What factors led to the success, or failure of Bank operations? Based on what has been learned, the paper provides suggestions about how the performance of future VET interventions can be improved. This review concerns itself primarily with implementation performance, and proposes measures to improve project outcomes.ICT Policy and Strategies,Health Economics&Finance,Health Monitoring&Evaluation,Teaching and Learning,Banks&Banking Reform

STRUCTURAL CHANGE OR LOGICAL INCREMENTALISM? TURBULENCE IN THE GLOBAL MEAT SYSTEM

In the last ten years the global meat industry has encountered numerous critical events related to food safety and food quality. These events in turn have caused the industry to re-evaluate how the meat supply chain functions and how to service the new social attributes demanded in the market place. Issues like source-verified, non-GMO, and organic are becoming important sources of product differentiation. How should firms in the meat supply chain respond? This study uses a needs assessment approach with meat supply chain managers and direct cataloguing of retail meat cases to better understand how the US meat supply chain is reacting to the turbulence in the industry.Livestock Production/Industries,

Initial Condition Sensitivity of Global Quantities in Magnetohydrodynamic Turbulence

In this paper we study the effect of subtle changes in initial conditions on the evolution of global quantities in two-dimensional Magnetohydrodynamic (MHD) turbulence. We find that a change in the initial phases of complex Fourier modes of the Els\"{a}sser variables, while keeping the initial values of total energy, cross helicity and Alfv\'{e}n ratio unchanged, has a significant effect on the evolution of cross helicity. On the contrary, the total energy and Alfv\'{e}n ratio are insensitive to the initial phases. Our simulations are based on direct numerical simulation using the pseudo-spectral method.Comment: 12 pages LateX, 11 ps figures. Accepted for publication by Physics of Plasma

The Asia-Pacific Regional Development Needs and Opportunities: An APAARI Perspective

Statement by William Dar and R. S. Paroda, Chairman and Executive Secretary respectively of the Asia Pacific Association of Agricultural Research Institutes (APAARI) on the priorities, and opportunities for collaborative agricultural research in Asia and the Pacific. The document was prepared for the first meeting of the Global Forum on Agricultural Research held at CGIAR International Centers Week, October-November 1996. It was circulated as an input to the GFAR discussions leading to a Declaration and Action Plan for Global Partnerships in Agricultural Research

Field theoretic calculation of scalar turbulence

The cascade rate of passive scalar and Bachelor's constant in scalar turbulence are calculated using the flux formula. This calculation is done to first order in perturbation series. Batchelor's constant in three dimension is found to be approximately 1.25. In higher dimension, the constant increases as $d^{1/3}$.Comment: RevTex4, publ. in Int. J. Mod. Phy. B, v.15, p.3419, 200