Asymmetric Non-Abelian Orbifolds and Model Building

The rules for the free fermionic string model construction are extended to include general non-abelian orbifold constructions that go beyond the real fermionic approach. This generalization is also applied to the asymmetric orbifold rules recently introduced. These non-abelian orbifold rules are quite easy to use. Examples are given to illustrate their applications.Comment: 30 pages, Revtex 3.

Magnetoelastic Torsional Vibration of Non-homogeneous Aeolotropic Cylindrical Shell of Viscoelastic Solids

This study investigates magnetoelastic torsional vibration of a non-homogeneous aeolotropic cylindrical shell of viscoelastic solids. The non-homogeneity of the shell obeyingpower law variation of elastic constants and density given by Aij= Crjf', p = por"(i, j = 1,2 ,... 6), where Cu (i, j = 1,2, ... 6) and po are constants and r is the radius vector. Frequency equation and phase velocity in several cases have been derived. Such problems of interaction of elastic  and electromagnetic fields have numerous applications in various branches of science, particularly in the detection of mechanical explosions in the interior of the earth and in the electromagnetic energy into vacuum

Wrapping the M Theory Five-Brane on K3

Using a recently constructed M5-brane world-volume action, we demonstrate that wrapping the M5-brane on K3 gives the heterotic string in seven dimensions. To facilitate the comparison, a new version of the world-sheet action for the Narain-compactified heterotic string, with manifest T duality invariance, is formulated.Comment: 14 pages, latex, no figures; an error has been correcte

Are Coronae of Magnetically Active Stars Heated by Flares? III. Analytical Distribution of Superimposed Flares

(abridged) We study the hypothesis that observed X-ray/extreme ultraviolet emission from coronae of magnetically active stars is entirely (or to a large part) due to the superposition of flares, using an analytic approach to determine the amplitude distribution of flares in light curves. The flare-heating hypothesis is motivated by time series that show continuous variability suggesting the presence of a large number of superimposed flares with similar rise and decay time scales. We rigorously relate the amplitude distribution of stellar flares to the observed histograms of binned counts and photon waiting times, under the assumption that the flares occur at random and have similar shapes. Applying these results to EUVE/DS observations of the flaring star AD Leo, we find that the flare amplitude distribution can be represented by a truncated power law with a power law index of 2.3 +/- 0.1. Our analytical results agree with existing Monte Carlo results of Kashyap et al. (2002) and Guedel et al. (2003). The method is applicable to a wide range of further stochastically bursting astrophysical sources such as cataclysmic variables, Gamma Ray Burst substructures, X-ray binaries, and spatially resolved observations of solar flares.Comment: accepted for publication in Ap

c=2 Rational Toroidal Conformal Field Theories via the Gauss Product

We find a concise relation between the moduli $\tau, \rho$ of a rational Narain lattice $\Gamma(\tau,\rho)$ and the corresponding momentum lattices of left and right chiral algebras via the Gauss product. As a byproduct, we find an identity which counts the cardinality of a certain double coset space defined for isometries between the discriminant forms of rank two lattices.Comment: AMS-TeX, 45 pages; title changed, minor errors corrected, acknowledgement adde

Quantum-gravity-induced matter self-interactions in the asymptotic-safety scenario

We investigate the high-energy properties of matter theories coupled to quantum gravity. Specifically, we show that quantum gravity fluctuations generically induce matter self-interactions in a scalar theory. Our calculations apply within asymptotically safe quantum gravity, where our results indicate that the UV is dominated by an interacting fixed point, with non-vanishing gravitational as well as matter couplings. In particular, momentum-dependent scalar self-interactions are non-zero and induce a non-vanishing momentum-independent scalar potential. Furthermore we point out that terms of this type can have observable consequences in the context of scalar-field driven inflation, where they can induce potentially observable non-Gaussianities in the CMB.Comment: 15 + 8 pages, 8 figures, extended truncation, version to be published in PR

Progress in Diarrheal Disease Research at Namru-2 in Collaboration with Badan Litbangkes and Rspi

Penyakit diare termasuk kolera masih merupakan masalah kesehatan yang penting untuk Indonesia. Kejadian luar biasa (KLB) "muntah-berak" masih terus dilaporkan dari berbagai daerah di Indonesia. Salah satu upaya yang dilakukan untuk mengatasi keadaan ini adalah menemukan suatu vaksin yang aman, praktis dan terjangkau harganya. CVD-103 adalah strain V. cholerae yang sebagian besar gen penyebab diare, toksin subunit A, telah dibuang. Pada penelitian dengan peserta anak-anak di Jakarta, CVD 103-HgR ternyata memberikan kenaikan antibodi dan dapat diterima baik oleh anak-anak Indonesia berusia 5-9 tahun dan 25-59 bulan. Di samping itu pemeriksaan sampel bakteriologik dari lingkungan dekat tempat kediaman peserta dengan menggunakan teknik yang peka untuk mendeteksi V. cholerae, tidak menemukan adanya strain vaksin. Suatu penelitian lapangan dengan tujuan untuk menilai kemanjuran dosis tunggal vaksin oral kolera CVD 103-HgR untuk pencegahan kolera secara klinis selama tiga tahun, telah dimulai didaerah Jakarta Utara pada tahun 1993. Selain itu penelitian ini juga bertujuan untuk menetapkan kemanjuran vaksin terhadap berbagai kelompok umur, terhadap kolera berat, serta membandingkan kemanjurannya pada peserta dengan golongan darah O. Jumlah penduduk yang ikut dalam penilaian vaksin ini adalah 67.000 peserta sukarela. Hasil penelitian ini diharapkan dapat diketahui pada akhir tahun 1996.Di samping penelitian tentang vaksin kolera, NAMRU dan Badan Litbangkes juga telah ikut serta dalam berbagai penelitian WHO, misalnya tentang larutan garam oralit (ORS) yang dilakukan di RS Karantina/RS Penyakit Infeksi Prof. Dr. Sulianti Saroso. Salah satu penelitian terakhir adalah manfaat larutan ORS dengan osmolaritas rendah pada tahun 1994. Hasil penelitian ini telah mendorong WHO untuk melaksanakan penelitian dengan larutan yang sama di berbagai pusat penelitian (multicenter) pada tahun 1995 sebelum mengusulkan suatu Perubahan formulasi larutan ORS secara global