Matter induced charge symmetry breaking and pion form factor in nuclear medium

Medium modification of pion form factor has been evaluated in asymmetric nuclear matter. It is shown that both the shape and the pole position of the pion form factor in dense asymmetric nuclear matter is different from its vacuum counterpart with $\rho$-$\omega$ mixing. This is due to the density and asymmetry dependent $\rho$-$\omega$ mixing which could even dominate over its vacuum counterpart in matter. Effect of the in-medium pion factor on experimental observables {\it e.g.}, invariant mass distribution of lepton pairs has been demonstrated.Comment: Final Version to appear in Jour. Phys.

Improving the Eleventh Graders's Recount Text Writing Through Mind Mapping Technique at SMA PSKD 7 Depok

The objective of this research was to improve the eleventh graders' recount text writing skill. To attain the objective a two-cycled classroom action research was conducted in SMA PSKD 7 Depok. The 28 students of the eleventh graders who participated in this research were taught recount text through mind mapping technique. The quantitative data, collected using tests, were analyzed by using statistical analysis technique. The qualitative data, collected using observation sheets and interview guide, were analyzed by using descriptive analysis technique. The results indicated that the mind mapping technique improved the eleventh graders' recount text writing skill, as shown by the increase of the mean scores of the tests conducted, i.e. 52,61 (in the pretest) to 70.61 ( post-test of cycle 1) to 80.29 (post-test of cycle 2). Based on the findings, it could be concluded that through implementation of mind mapping technique, students' recount text writing skill could improve. Keywords: Mind mapping technique, writing skill, classroom action researc

Thermal conductivity and diffusion-mediated localization in Fe_{1-x}Cr_{x} Alloys

We apply a new Kubo-Greenwood type formula combined with a generalized Feynman diagram- matic technique to report a first principles calculation of the thermal transport properties of disordered Fe_{1-x}Cr_{x} alloys. The diagrammatic approach simplifies the inclusion of disorder-induced scattering effects on the two particle correlation functions and hence renormalizes the heat current operator to calculate configuration averaged lattice thermal conductivity and diffusivity. The thermal conductivity K(T) in the present case shows an approximate quadratic T-dependence in the low temperature regime (T < 20 K), which subsequently rises smoothly to a T-independent saturated value at high T . A numerical estimate of mobility edge from the thermal diffusivity data yields the fraction of localized states. It is concluded that the complex disorder scattering processes, in force-constant dominated disorder alloys such as Fe-Cr, tend to localize the vibrational modes quite significantly.Comment: 5 pages, 5 figure

Hybrid Chaplygin gas and phantom divide crossing

Hybrid Chaplygin gas model is put forward, in which the gases play the role of dark energy. For this model the coincidence problem is greatly alleviated. The effective equation of state of the dark energy may cross the phantom divide $w=-1$. Furthermore, the crossing behaviour is decoupled from any gravity theories. In the present model, $w<-1$ is only a transient behaviour. There is a de Sitter attractor in the future infinity. Hence, the big rip singularity, which often afflicts the models with matter whose effective equation of state less than -1, is naturally disappear. There exist stable scaling solutions, both at the early universe and the late universe. We discuss the perturbation growth of this model. We find that the index is consistent with observations.Comment: 11 pages, 4 figures, V3: discussions on the perturbation growth added, V4: minor corrections, to match the published versio

Low Ply Drawings of Trees

We consider the recently introduced model of \emph{low ply graph drawing}, in which the ply-disks of the vertices do not have many common overlaps, which results in a good distribution of the vertices in the plane. The \emph{ply-disk} of a vertex in a straight-line drawing is the disk centered at it whose radius is half the length of its longest incident edge. The largest number of ply-disks having a common overlap is called the \emph{ply-number} of the drawing. We focus on trees. We first consider drawings of trees with constant ply-number, proving that they may require exponential area, even for stars, and that they may not even exist for bounded-degree trees. Then, we turn our attention to drawings with logarithmic ply-number and show that trees with maximum degree $6$ always admit such drawings in polynomial area.Comment: This is a complete access version of a paper that will appear in the proceedings of GD201

Perancangan Antena Mikrostrip Bentuk Segiempat Dual Frequency untuk Aplikasi WLAN 2400 Mhz dan 5000 Mhz

— Dalam penelitian ini dilakukan perancangan antena mikrostrip bentuk segiempat untuk frekuensi 2400 MHz dan 5000 MHz memenuhi standar WLAN IEEE 802.11b dan IEEE 802.11a. Antena ini memiliki impedansi masukan sebesar 50 Ω dengan ukuran patch segiempat W = 30 mm dan L = 29 mm menggunakan substrat FR4 (h = 1,6 mm). Lebar saluran pencatu adalah 3,1 mm dengan panjang 6 mm. Untuk menghasilkan dual frequency, dilakukan dengan menambahkan beban slit pada patch antena. Dari hasil simulasi diperoleh nilai return loss sebesar -13,06 dB untuk frekuensi 2400 MHz dan -31,64 dB untuk frekuensi 5000 MHz dengan nilai VSWR sebesar 1,575 untuk 2400 MHz dan 1,054 untuk 5000 MHz. Bandwidth pada frekuensi 2400 MHz dan 5000 MHz berturut-turut adalah 134 MHz (5,58%) dan 630 MHz (12,6%). Prototipe dari antena yang dirancang telah dipabrikasi, namun belum dilakukan pengujian. Rancangan yang sederhana namun mampu memenuhi tujuan yang diinginkan merupakan keunggulan dibandingkan penelitian sebelumnya. Kata kunci — Antena mikrostrip, segiempat, WLAN, dual frequency, beban sli