Critical Level Statistics of the Fibonacci Model

We numerically analyze spectral properties of the Fibonacci model which is a one-dimensional quasiperiodic system. We find that the energy levels of this model have the distribution of the band widths $w$ obeys $P_B(w)\sim w^{\alpha}$ $(w\to 0)$ and $P_B(w) \sim e^{-\beta w}$ $(w\to\infty)$, the gap distribution $P_G(s)\sim s^{-\delta}$ $(s\to 0)$ ($\alpha,\beta,\delta >0$) . We also compare the results with those of multi-scale Cantor sets. We find qualitative differences between the spectra of the Fibonacci model and the multi-scale Cantor sets.Comment: 7 page

Bahan Ajar Alat Ukur Dan Pengukuran Fisika Berbasis Inkuiri Terbimbing

: This research to determine the feasibility, effectiveness of teaching materials measuring instrument and measurement physics in increasing science process skills and mastery of concepts students. The research design using the design development of Borg & Gall. The effectiveness of teaching materials tested under 2 steps, before the mid-term exam and final exam of the semester. The research showed that the teaching materials of measurement and instrument measurement of physics-based guided inquiry developed,: 1) is under fairly feasible category to be implemented, 2) adequates to improve the process science skills of students, 3) improves mastery of concepts. Step one indicates the presence of correlation between science process skills and mastery concept of the students. The next step shows no correlation between them

Sistem Keamanan Jaringan Local Area Network Menggunakan Teknik De-militarized Zone

  Islamic University”45” computer network needs a safe network to strengthen the network security systems to protect servers from attacks such as Port Scanning and DoS attack (Denial of Service). One of the network security techniques is De-Militarized Zone (DMZ) that is a mechanism to protect the internal system from hacker attacks or other parties who want to enter the system with no access. The purpose of this Project is to implement LAN network security system using De-Militarized Zone (DMZ) technique, with a single firewall that supports the internal and external networks. The results of the DMZ technique implementation at the Islamic University\u27s "45", it is found that filter DoS attack can be implemented well.  Data analysis results show DoS attack with the type of ICMP Flooding attack, and UDP Flooding attack can be blocked with Percentage of success is 98%.   Keywords : attack, network security,  de-militarized zone   &nbsp

Slave-Boson Three-Band Model with O-O Hopping for High-Tc Superconductors

Slave boson mean-field approximation is carried out analytically for weakly doped CuO_2 conduction planes, characterized by Cu-O charge transfer energy \Delta_{pd}, Cu-O hopping t_0, O-O hopping t' and repulsion U_d between holes on Cu site taken as infinite. At zero doping \delta, finite negative t',|t'|<t_0/2, expands the range of stability of the covalent, conducting state on the expense of the insulating state which, however, remains stable at larger \Delta_{pd}. For sufficiently large \Delta_{pd} the renormalized charge transfer energy saturates at 4|t'| instead of decreasing to zero, as at t'=0 case. In contrast to t', finite \delta suppresses the insulating state nearly symmetrically with respect to the sign of \delta. The regime with charge transfer energy renormalized close to 4|t'| fits remarkably well the ARPES spectra of Bi2212 and LSCO, and, in the latter case, explains the observed strong doping dependence of the Cu-O hopping.Comment: 4 pages, 2 figure

The Haldane-Rezayi Quantum Hall State and Magnetic Flux

We consider the general abelian background configurations for the Haldane-Rezayi quantum Hall state. We determine the stable configurations to be the ones with the spontaneous flux of $(\Z+1/2) \phi_0$ with $\phi_0 = hc/e$. This gives the physical mechanism by which the edge theory of the state becomes identical to the one for the 331 state. It also provides a new experimental consequence which can be tested in the enigmatic $\nu=5/2$ plateau in a single layer system.Comment: RevTex, 5 pages, 2 figures. v2:minor corrections. v4: published version. Discussion on the thermodynamic limit adde

SOCIAL MEDIA AS A CONDUIT FOR TEACHER PROFESSIONAL DEVELOPMENT IN THE DIGITAL ERA: MYTHS, PROMISES OR REALITIES?

It is generally accepted that effective teacher professional development is critical to effective educational improvements and reforms of any educational institution. However, a conventional form of teacher professional development is constrained by time and space and, more often than not, there is a lack of perpetual support to teachers in the wake of a training program. An alternative way of teacher professional development therefore needs to be sought. This article argues that social media and all its facets open up new avenues for sustainable professional development and life-long learning in which case support can be obtained through virtual learning communities

One-dimensional metallic behavior of the stripe phase in La2−x_{2-x}Srx_xCuO4_4

Using an exact diagonalization method within the dynamical mean-field theory we study stripe phases in the two-dimensional Hubbard model. We find a crossover at doping $\delta\simeq 0.05$ from diagonal stripes to vertical site-centered stripes with populated domain walls, stable in a broad range of doping, $0.05<\delta<0.17$. The calculated chemical potential shift $\propto -\delta^2$ and the doping dependence of the magnetic incommensurability are in quantitative agreement with the experimental results for doped La$_{2-x}$Sr$_x$CuO$_4$. The electronic structure shows one-dimensional metallic behavior along the domain walls, and explains the suppression of spectral weight along the Brillouin zone diagonal.Comment: 4 pages, 4 figure

Field theory of spin-singlet quantum Hall states

We formulate a field theory for a class of spin-singlet quantum Hall states (the Haldane-Rezayi state and its variants) which have been proposed for the quantized Hall plateaus observed at the second lowest Landau level. A new essential ingredient is a class of super Chern-Simons field. We show that the known properties of the states are consistently described by it. We also give a 2+1 dimensional hierarchical construction. Implications of the proposal are discussed and a new physical picture of composite particles at the second lowest Landau level emerges.Comment: RevTex, 5 pages, 1 figur

Effect of Stripes on Electronic States in Underdoped La_{2-x}Sr_xCuO_4

We investigate the electronic states of underdoped La_{2-x}Sr_xCuO_4 (LSCO) by using a microscopic model, i.e., t-t'-t''-J model, containing vertical charge stripes. The numerically exact diagonalization calculation on small clusters shows the consistent explanation of the physical properties in the angle-resolved photoemission, neutron magnetic scattering and optical conductivity experiments such as the antiphase domain and quasi-one-dimensional charge transport. The pair correlation function of the d-channel is suppressed by the stripes. These results demonstrate a crucial role of the stripes in LSCOComment: 4 pages, 4 EPS figures, revised version, to appear in Phys. Rev. Lett. Vol.82, No.25, 199