Magnetic fields and the Weyl tensor in the early universe

We have solved the Einstein-Maxwell equations for a class of isotropic metrics with constant spatial curvature in the presence of magnetic fields. We consider a slight modification of the Tolman averaging relations so that the energy-momentum tensor of the electromagnetic field possesses an anisotropic pressure component. This inhomogeneous magnetic universe is isotropic and its time evolution is guided by the usual Friedmann equations. In the case of flat universe, the space-time metric is free of singularities (except the well-known initial singularity at t = 0). It is shown that the anisotropic pressure of our model has a straightforward relation to the Weyl tensor. We also analyze the effect of this new ingredient on the motion of test particles and on the geodesic deviation of the cosmic fluid.Comment: 10 pages, 2 figures, new conceptual treatment of the early phenomenological work arXiv:1301.3079. Matches published versio

High-Resolution Imaging and Optical Control of Bose-Einstein Condensates in an Atom Chip Magnetic Trap

A high-resolution projection and imaging system for ultracold atoms is implemented using a compound silicon and glass atom chip. The atom chip is metalized to enable magnetic trapping while glass regions enable high numerical aperture optical access to atoms residing in the magnetic trap about 100 microns below the chip surface. The atom chip serves as a wall of the vacuum system, which enables the use of commercial microscope components for projection and imaging. Holographically generated light patterns are used to optically slice a cigar-shaped magnetic trap into separate regions; this has been used to simultaneously generate up to four Bose-condensates. Using fluorescence techniques we have demonstrated in-trap imaging resolution down to 2.5 micronsComment: 4 pages, 5 figures, 12 reference

Optimized bio-inspired kernels with twin support vector machine using low identity sequences to solve imbalance multiclass classification

The function of enzymes is performed differently depending on their bio-chemical mechanisms and important to the prediction of protein structure and function. In order to overcome the weaknesses of imbalance data distribution in subclasses prediction we proposed Bio-Twin Support Vector Machine (Bio–TWSVM). The TWSVM approach as also allow for kernel optimization where in this study we have introduced the bio-inspired kernels such as the Fisher, spectrum and mismatch kernels which at the same time incorporate the biological information regarding the protein evolution in the classification process

Improved Astrometry and Photometry for the Luyten Catalog. I. Bright Stars

We outline the construction of an updated version of the New Luyten Two-Tenths (NLTT) catalog of high proper motion stars, which will contain improved astrometry and photometry for the vast majority of the ~59,000 stars in NLTT. The bright end is constructed by matching NLTT stars to Hipparcos, Tycho-2, and Starnet; the faint end by matching to USNO-A and 2MASS. In this first paper, we detail the bright-end matching procedure. We show that for the majority of stars in his catalog, Luyten measured positions accurate to 1" even though he recorded his results much more coarsely. However, there is a long tail of position errors, with one error as large as 11 deg. Proper-motion errors for the stars with small position errors are 24 mas/yr (1 sigma) but deteriorate to 34 mas/yr for stars with inferior positions. NLTT is virtually 100% complete for V15 deg, but completeness in this magnitude range falls to about 75% at the Galactic plane. Incompleteness near the plane is not uniform, but is rather concentrated in the interval -80<l<20, where the Milky Way is brightest.Comment: Submitted to ApJ, 28 pages including 7 figure

No nearby counterparts to the moving objects in the Hubble Deep Field

Ibata et al (1999) have recently discovered faint, moving objects in the Hubble Deep Field. The quantity, magnitudes and proper motions of these objects are consistent with old white dwarfs making up the Galactic dark halo. We review a number of ground-based proper motion surveys in which nearby dark halo white dwarfs might be present, if they have the colours and absolute magnitudes proposed. No such objects have been found, whereas we argue here that several times more would be expected than in the Hubble Deep Field. We conclude it is unlikely that hydrogen atmosphere white dwarfs make up a significant fraction of the halo dark matter. No limits can be placed yet on helium atmosphere dwarfs from optical searches.Comment: 7 pages, 4 figures, MNRAS LaTeX forma

A Compact Microchip-Based Atomic Clock Based on Ultracold Trapped Rb Atoms

We propose a compact atomic clock based on ultracold Rb atoms that are magnetically trapped near the surface of an atom microchip. An interrogation scheme that combines electromagnetically-induced transparency (EIT) with Ramsey's method of separated oscillatory fields can achieve atomic shot-noise level performance of 10^{-13}/sqrt(tau) for 10^6 atoms. The EIT signal can be detected with a heterodyne technique that provides noiseless gain; with this technique the optical phase shift of a 100 pW probe beam can be detected at the photon shot-noise level. Numerical calculations of the density matrix equations are used to identify realistic operating parameters at which AC Stark shifts are eliminated. By considering fluctuations in these parameters, we estimate that AC Stark shifts can be canceled to a level better than 2*10^{-14}. An overview of the apparatus is presented with estimates of duty cycle and power consumption.Comment: 15 pages, 11 figures, 5 table

Produksi dan Kandungan Hara Serasah pada Hutan Rakyat Nglanggeran, Gunung Kidul, D.i. YOGYAKARTA

Bentuk pengelolaan khas hutan rakyat di Desa Nglanggeran, Kecamatan Patuk, Kabupaten Gunung Kidul, ada tiga macam, yaitu alas (hutan), pekarangan, dan tegalan. Penelitian ini bertujuan untuk mengetahui produksi dan jenis serasah dominan serta menganalisis kandungan nutrisinya sehingga dapat menjadi bahan pertimbangan dalam pemilihan jenis yang dapat menambah unsur hara pada tanah. Hasil penelitian menunjukkan urutan produksi serasah adalah dari HR3 (6,05 ton/ha/6bln), HR2 (5,64 ton/ha/6 bln) dan HR1 (4,61 ton/ha/6 bln). Berat serasah daun sebesar 5,150 ton/ha (77,07%) di HR3, 5,218 ton/ha (76,22%) di HR2 dan 3,816 ton/ha (66,96 %) di HR1. Produksi serasah tersebut jika terdekomposisi sempurna selama 6 bulan akan menambah unsur hara ke tanah HR3 sebesar 80,56 kg/haN; 3,50 kg/ha P; dan 14,73 kg/ha K, HR2 (69,58 kg/ha N; 3,38 kg/ha P; dan 14,28 kg/ha K), dan paling rendah pada HR1 (53,15 kg/ha N; 1,95 kg/ha P dan 7,18 kg/ha K). Untuk memenuhi kebutuhan hara baik tanaman pertanian maupun tanaman hutan (pohon) kandungan hara serasah ini belum mencukupi sehingga perlu dikombinsikan dengan jenis lain seperti legum

Model Volatilitas Garch(1,1) Dengan Error Student-t Untuk Kurs Beli Eur Dan Jpy Terhadap Idr

Studi ini menyajikan model volatilitas Generalized Autoregressive Conditional Heteroscedasticity (GARCH)(1,1) untuk returns keuangan yang mengasumsikan bahwa returns error berdistribusi Student-t. Parameter dari model volatilitas diestimasi menggunakan algoritma Markov Chain Monte Carlo (MCMC). Secara khusus, nilai-nilai parameter model dibangkitkan menggunakan metode adaptive random walk Metropolis dan independence chain Metropolis–Hasting (IC-MH) yang dikonstruksi dalam algoritma MCMC. Model dan metode diaplikasikan pada data kurs beli harian Yen Jepang (JPY) dan Euro (EUR) terhadap Rupiah Indonesia (IDR) pada periode Januari 2009 sampai dengan Desember 2014. Berdasarkan kriteria faktor Bayes, hasil empiris menunjukkan dukungan sangat kuat terhadap asumsi distribusi student-t untuk returns error.This study investigates a volatility GARCH(1,1) model with Student's t-error distribution for financial return. The parameters of GARCH model are estimated by using Markov Chain Monte Carlo (MCMC) algorithm. Specifically, the draws are sampled using adaptive random walk Metropolis and independence chain Metropolis–Hastings (IC-MH) methods that constructed in the MCMC algorithm. The model and methods are applied to the daily buying rate data of the Euro (EUR) and Japanese Yen (JPY) to Indonesian Rupiah (IDR) from January 2009 to December 2014. According to the Bayes factor criteria, empirical results shows a strong support to the assumption of Student's t-error distribution

Analisa Pola Bidang Sesar pada Zona Subduksi di Wilayah Selatan Pulau Sumatera dari Event Gempa pada Tahun 2011-2014

Pada penelitian membahas tentang momen tensor dan pola bidang patahan yang didapat dari focal mechanism gempa di selatan Pulau Sumatera Indonesia menempati zona tektonik yang sangat aktif karena tiga lempeng besar dunia dan sembilan lempeng kecil lainnya saling bertemu di wilayah Indonesia, gempa-gempa yang terjadi di Pulau Sumatera merupakan implikasi geodinamika dari deformasi aktif di sekitar Sunda dan Java trench, dalam menentukan momen tensor dan focal mechanism-nya menggunakan program ISOLA-GUI. Data yang digunakan dalam penelitian ini mempunyai magnituda lebih dari sama dengan 5.5 Skala Ritcher. Dari hasil penelitian didapatkan bahwa berdasarkan pengolahan data gempa yang diakibatkan oleh Sesar Mentawai mempunyai pola sesar reverse fault dan pola sesar dip-slip. Dalam penelitian ini didapatkan besar rentang momen tensor untuk masing-masing komponennya sebesar M11 =2.531 exp15 sampai 0.205 exp18, M22 = 3.495 exp15 sampai 0.337 exp18, M33 = 0.964 exp15 sampai 0.131 exp18, M31 = 0.544 exp15 sampai 5.174 exp18, M32 = 1.107 exp15 sampai 4.113 exp18, dan M12 = 1.140 exp15 sampai 0.430 exp18 dan besar slip rata-rata adalah 274.71 meter