P enerapan Model Pembelajaran Cooperative Learning ( Teknik Jigsaw ) u ntuk Meningkatkan Motivasi d an Prestasi Belajar Siswa k e las IV SDN J e rukmipis d alam Pembelajaran IPS p ada Pokok Bahasan Peta Lingkungan Setempat (Penilitian Tindakan Kelas IV SDN Jerukmipis Kecamatan Solokan Jeruk Kabupaten Bandung )

Penelitian Tindakan Kelas (PTK) ini bertujuan untuk memperbaiki kualit as pembelajaran di SDN Jerukmipis Bandung khususnya di kelas I V pada mata pelajara IPS tentang P eta L ingkungan S etempat dengan menggunakan model cooperative learning teknik Jigsaw . Penel itian ini dilatar belakangi dengan adanya temuan masalah yang ditemui oleh peneliti p ada saat melaksanakan observasi. Permasalahan tersebut yaitu adanya penurunan motivasi belajar peserta didik sehingga menyebabkan hasil belajar siswa menurun sehingga meny ebabkan 50% siswa belum mencapai kriteria ketuntasan minimal (KKM) yang ditetapkan. Permasalah an ini muncul disebabkan karena guru kurang melibatkan siswa secara aktif selama proses pembelajaran sehingga motivasi belajar siswa masih rendah yang menyebabkan siswa menjadi bosan dan malas untuk mengikuti pembelajaran. Penelitian ini dilaksanakan dalam 2 siklus, setiap siklusnya terdiri dari 1 kali pertemuan atau pembelajaran, adapun tahapan dalam penelitian yaitu tahap perencanaan, pelaksanaan, observasi, anal isis dan refleksi. Intrumen yang digunakan dalam penelitian ini berupa lembar observasi dan tes evaluasi hasil belajar yang dilakukan melalui post tes.Hasil penelitian ini menunjukkan adanya peningkatan motivasi dan hasil belajar siswa pada setiap siklusny a. Jika dilihat dari hasil belajar pa da siklus I dari jumlah siswa 25 or ang, siswa yang mencapai KKM 73 %. Pada siklus ke - II terdapat peningkatan si swa yang mencapai KKM sebesar 92 %. Sedangkan dari motivasi belajar siswa pada siklus I siswa yang me mperoleh menunjukkan kriterian ketuntasan sebesar 73% dengan kriteria baik selanjutnya pada siklus ke - II meningkat menjadi 92% dengan kriteria sangat baik. Dari penelitian tersebut maka dapat disimpulkan bahwa pembelaj aran dengan menerapkan model Cooperative Learni ng teknik Jigsaw dapat meningkatkan motivasi dan hasil belajar siswa kelas I V SDN Jerukmipis Bandung pada mata pelajaran IPS tentang Peta Lingkungan Setempat . Kata Kunci : Motivasi d an Prestasi Belajar Siswa. Model Cooperative Learning T eknik Jigsaw

Parton recombination at all pTp_T

Hadron production at all $p_T$ in heavy-ion collisions in the framework of parton recombination is reviewed. It is shown that the recombination of thermal and shower partons dominates the hadron spectra in the intermediate $p_T$ region. In $d+Au$ collisions, the physics of particle production at any $\eta$ is basically the same as at $\eta=0$. The Cronin effect is described as a result of the final-state instead of the initial-state interaction. The suppression of $R_{CP}$ at high $\eta$ is due to the reduction of the soft parton density on the deuteron side, thus resulting in less pions produced by recombination, an explanation that requires no new physics. In $Au+Au$ collisions large $p/\pi$ ratio is obtained because the thermal partons can contribute to the formation of proton more than they do to the pion.Comment: 12 pages + 5 figures. Invited talk at Hard Probes 200

A description of the ratio between electric and magnetic proton form factors by using space-like, time-like data and dispersion relations

We use the available information on the ratio between the electric and magnetic proton form factors coming from recently published space-like data and from the few available time-like data. We apply a dispersive procedure on these data to evaluate the behaviour of this ratio, as a complex function, for all values of q^2.Comment: 12 pages, 7 Encapsulated Postscript figures, uses epsfig, rotating, exscale, amsmath, cite, latexsym, graphics, color packages, added reference

Influence of the microstructure on fatigue and fracture toughness properties of large heat-treated mold steels

The standard ISO 1.2738 medium-carbon low-alloy steel has long been used to fabricate plastic molds for injection molding of large automotive components, such as bumpers and dashboards. These molds are usually machined from large pre-hardened steel blooms. Due to the bloom size, the heat treatment yields mixed microstructures, continuously varying from surface to core. Negative events (such as microcracks due to improper weld bed deposition or incomplete extraction of already formed plastic objects) or too large thermal/mechanical stresses can conceivably cause mold failure during service due to the low fracture toughness and fatigue resistance typically encountered in large slack quenched and tempered ISO 1.2738 steel blooms. Alternative steel grades, including both non-standard microalloyed steels, designed for the same production process, and precipitation hardening steels, have recently been proposed by steelworks. However, the fracture toughness and the fatigue properties of these steels, and hence their response during the service, are not well known. Results of an experimental campaign to assess the fracture toughness and fatigue properties, as well as the basic mechanical properties, of a microalloyed and a precipitation hardening plastic mold steel blooms are presented and commented, also in respect to the results previously obtained by two commercial ISO 1.2738 ones. Experimental results show that these steels generally exhibit low fracture toughness values; in the traditional quenched and tempered bloom steels the brittleness may be caused both by the presence of mixed microstructures and by grain boundaries segregation, while in the precipitation hardened one the brittleness probably stems from the precipitation phenomena. This study suggests that microalloyed and precipitation hardening steels may be used to produce large plastic mold, yet the fracture toughness still remains the most critical propert

Googling the brain: discovering hierarchical and asymmetric network structures, with applications in neuroscience

Hierarchical organisation is a common feature of many directed networks arising in nature and technology. For example, a well-defined message-passing framework based on managerial status typically exists in a business organisation. However, in many real-world networks such patterns of hierarchy are unlikely to be quite so transparent. Due to the nature in which empirical data is collated the nodes will often be ordered so as to obscure any underlying structure. In addition, the possibility of even a small number of links violating any overall “chain of command” makes the determination of such structures extremely challenging. Here we address the issue of how to reorder a directed network in order to reveal this type of hierarchy. In doing so we also look at the task of quantifying the level of hierarchy, given a particular node ordering. We look at a variety of approaches. Using ideas from the graph Laplacian literature, we show that a relevant discrete optimization problem leads to a natural hierarchical node ranking. We also show that this ranking arises via a maximum likelihood problem associated with a new range-dependent hierarchical random graph model. This random graph insight allows us to compute a likelihood ratio that quantifies the overall tendency for a given network to be hierarchical. We also develop a generalization of this node ordering algorithm based on the combinatorics of directed walks. In passing, we note that Google’s PageRank algorithm tackles a closely related problem, and may also be motivated from a combinatoric, walk-counting viewpoint. We illustrate the performance of the resulting algorithms on synthetic network data, and on a real-world network from neuroscience where results may be validated biologically

P and CP violation in B physics

While the Kobayashi--Maskawa single phase origin of CP violation passed its first crucial precision test in $B\to J/\psi K_S$, the chirality of weak $b$-quark couplings has not yet been carefully tested. We discuss recent proposals for studying the chiral and CP-violating structure of these couplings in radiative and in hadronic B decays.Comment: 15 pages, talk at PASCOS'03, Tata Inst., Mumbai, Jan. 200

Amicable pairs and aliquot cycles for elliptic curves

An amicable pair for an elliptic curve E/Q is a pair of primes (p,q) of good reduction for E satisfying #E(F_p) = q and #E(F_q) = p. In this paper we study elliptic amicable pairs and analogously defined longer elliptic aliquot cycles. We show that there exist elliptic curves with arbitrarily long aliqout cycles, but that CM elliptic curves (with j not 0) have no aliqout cycles of length greater than two. We give conjectural formulas for the frequency of amicable pairs. For CM curves, the derivation of precise conjectural formulas involves a detailed analysis of the values of the Grossencharacter evaluated at a prime ideal P in End(E) having the property that #E(F_P) is prime. This is especially intricate for the family of curves with j = 0.Comment: 53 page