A detailed analysis of structure growth in f(R)f(R) theories of gravity

We investigate the connection between dark energy and fourth order gravity by analyzing the behavior of scalar perturbations around a Friedmann-Robertson-Walker background. The evolution equations for scalar perturbation are derived using the covariant and gauge invariant approach and applied to two widely studied $f(R)$ gravity models. The structure of the general fourth order perturbation equations and the analysis of scalar perturbations lead to the discovery of a characteristic signature of fourth order gravity in the matter power spectrum, the details of which have not seen before in other works in this area. This could provide a crucial test for fourth order gravity on cosmological scales.Comment: 27 pages and 35 figure

A Program Evaluation of Intersession Tutoring

This study examined one program which was in place in a multi-track year-round elementary school, a tutoring program delivered during the students\u27 intersession. Through interviews, surveys, and analysis of grades recorded on report cards, the program was evaluated to determine whether goals for the program were met. Survey data revealed that students, parents, and teachers all felt overwhelmingly that the program was effective at meeting stated program goals. Report card data did not show a statistically significant increase in grades after students attended the program, but many intervening variables were not controlled for. Additional convenience factors, such as transportation, cost, and timing contributed to the program benefit

Cosmo-dynamics and dark energy with a quadratic EoS: anisotropic models, large-scale perturbations and cosmological singularities

In general relativity, for fluids with a linear equation of state (EoS) or scalar fields, the high isotropy of the universe requires special initial conditions, and singularities are anisotropic in general. In the brane world scenario anisotropy at the singularity is suppressed by an effective quadratic equation of state. There is no reason why the effective EoS of matter should be linear at the highest energies, and a non-linear EoS may describe dark energy or unified dark matter (Paper I, astro-ph/0512224). In view of this, here we study the effects of a quadratic EoS in homogenous and inhomogeneous cosmological models in general relativity, in order to understand if in this context the quadratic EoS can isotropize the universe at early times. With respect to Paper I, here we use the simplified EoS P=alpha rho + rho^2/rho_c, which still allows for an effective cosmological constant and phantom behavior, and is general enough to analyze the dynamics at high energies. We first study anisotropic Bianchi I and V models, focusing on singularities. Using dynamical systems methods, we find the fixed points of the system and study their stability. We find that models with standard non-phantom behavior are in general asymptotic in the past to an isotropic fixed point IS, i.e. in these models even an arbitrarily large anisotropy is suppressed in the past: the singularity is matter dominated. Using covariant and gauge invariant variables, we then study linear perturbations about the homogenous and isotropic spatially flat models with a quadratic EoS. We find that, in the large scale limit, all perturbations decay asymptotically in the past, indicating that the isotropic fixed point IS is the general asymptotic past attractor for non phantom inhomogeneous models with a quadratic EoS. (Abridged)Comment: 16 pages, 6 figure

Sistem Automasi Proses Produksi Minuman Dengan Sistem SCADA Menggunakan PLC

Industries need production processes that can be operated continually from one process to another without a lot of human energy resources. The solution of the problem is using an automation system which can be worked and operated from one central operator. SCADA with PLC can be used in many industrial processes because it can answer all the problems in controlling industrial application automatically. This paper describe how to make a design of simulation plant for beverages production process. The plant will use : pumps, mixer, valves, and heater. This plant will be operated by PLC Omron C-200 HS which is connected to SCADA Intouch, Wonderware Production. The comunication between PLC Omron and SCADA Intouch use Host Link RS 232c with I/O Servers program. The result from the simulation plant design for the minimum power shaft pump is 6.788 Watt. The mixer need a motor with speed 114 rpm. And the heater need 1000 Watt at 01:44:21.64. While the minimum valve design is needed to hold the fluids pressure until 106,4096 KPa

Exploring the role of low-density neutrophils during Mycobacterium tuberculosis infection

Tuberculosis (TB) is caused by infection with the bacteriu

Corrosion resistant behaviour of PANI–metal bilayer coatings

The present work discusses on the corrosion resistant behaviour of polymer metal bilayer coatings, viz. polyaniline (PANI), polyaniline–nickel (PANI–Ni), nickel–polyaniline (Ni–PANI), polyaniline–zinc (PANI–Zn) and zinc–polyaniline (Zn–PANI). The coatings were synthesized by means of cyclic voltametric method. The coatings thus obtained were uniform in nature and highly adherent to the mild steel substrate. The effectiveness of the coatings in preventing corrosion was tested by electrochemical impedance studies (EIS) using Nyquist and Bode plots and potentiodynamic polarization studies as well. Among the various coatings synthesized, the PANI–Zn coating was found to offer the maximum protection, followed by PANI–Ni coatings. Metal–PANI coatings were found to offer the least resistance to corrosion. The coatings thus obtained were characterized by scanning electron microscopic (SEM) analysis and the results are discussed

A simplified structure for the second order cosmological perturbation equations

Increasingly accurate observations of the cosmic microwave background and the large scale distribution of galaxies necessitate the study of nonlinear perturbations of Friedmann-Lemaitre cosmologies, whose equations are notoriously complicated. In this paper we present a new derivation of the governing equations for second order perturbations within the framework of the metric-based approach that is minimal, as regards amount of calculation and length of expressions, and flexible, as regards choice of gauge and stress-energy tensor. Because of their generality and the simplicity of their structure our equations provide a convenient starting point for determining the behaviour of nonlinear perturbations of FL cosmologies with any given stress-energy content, using either the Poisson gauge or the uniform curvature gauge.Comment: 30 pages, no figures. Changed title to the one in published version and some minor changes and addition

Kontrol Gerakan Buka Tutup Pintu Untuk Akses Sistem Keamanan Menggunakan Pola Iris Mata Manusia

Saat ini sistem keamanan konvensional seperti password atau kartu sudah tidak handal lagi karena keamanan sistem dapat ditembus oleh para pihak yang tidak berwenang menggunakan password atau kartu seseorang. Oleh karena itu dikembangkan sistem biometrik yang berdasarkan pada karakteristik alami manusia yaitu karakteristik fisiologis dan karakteristik perilaku seperti wajah, sidik jari, iris mata, retina mata, DNA, tanda tangan, dan suara, dimana sistem tersebut tidak mudah dicuri atau digunakan oleh pihak yang tidak berwenang.Dalam paper ini akan diusulkan suatu sistem keamanan akses menggunakan pengenalan pola iris mata dengan arsitektur JST yaitu Jaringan Propagasi Balik menggunakan program Matlab. Setelah berhasil dilakukan pengenalan pola iris mata maka dilakukan kontrol yang sesuai, dalam bahasan ini menggunakan mikrokontroler AT Mega 8535 sebagai pemroses data yang masuk untuk mengendalikan otomatisasi buka tutup pintu . Sistem ini dicoba diterapkan dalam sistem keamanan pada pintu masuk sebuah ruangan yang penting dimana hanya orang-orang tertentu saja yang boleh masuk. Sehingga apabila data iris mata sesuai dengan pola, maka pintu ruangan dapat terbuka. Sebaliknya bila pola iris mata tidak dikenali maka pintu tidak akan terbuka