7,716 research outputs found
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.
Mechanisms operating during plastic deformation of metals under concurrent production of cascades and dislocations
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
A General Treatment of One- to Three-Dimensional Diffusion Reaction Kinetics of Interstitial Clusters: Implications for the Evolution of Voids
c=2 Rational Toroidal Conformal Field Theories via the Gauss Product
We find a concise relation between the moduli of a rational
Narain lattice 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
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