39 research outputs found
Limits on Production of Magnetic Monopoles Utilizing Samples from the DO and CDF Detectors at the Tevatron
We present 90% confidence level limits on magnetic monopole production at the
Fermilab Tevatron from three sets of samples obtained from the D0 and CDF
detectors each exposed to a proton-antiproton luminosity of
(experiment E-882). Limits are obtained for the production cross-sections and
masses for low-mass accelerator-produced pointlike Dirac monopoles trapped and
bound in material surrounding the D0 and CDF collision regions. In the absence
of a complete quantum field theory of magnetic charge, we estimate these limits
on the basis of a Drell-Yan model. These results (for magnetic charge values of
1, 2, 3, and 6 times the minimum Dirac charge) extend and improve previously
published bounds.Comment: 18 pages, 17 figures, REVTeX
Improved Experimental Limits on the Production of Magnetic Monopoles
We present new limits on low mass accelerator-produced point-like Dirac
magnetic monopoles trapped and bound in matter surrounding the D\O collision
region of the Tevatron at Fermilab (experiment E-882). In the context of a
Drell-Yan mechanism, we obtain cross section limits for the production of
monopoles with magnetic charge values of 1, 2, 3, and 6 times the minimum Dirac
charge of the order of picobarns, some hundred times smaller than found in
similar previous Fermilab searches. Mass limits inferred from these cross
section limits are presented.Comment: 5 pages, 4 eps figures, REVTe
Violations of local realism with quNits up to N=16
Predictions for systems in entangled states cannot be described in local
realistic terms. However, after admixing some noise such a description is
possible. We show that for two quNits (quantum systems described by N
dimensional Hilbert spaces) in a maximally entangled state the minimal
admixture of noise increases monotonically with N. The results are a direct
extension of those of Kaszlikowski et. al., Phys. Rev. Lett. {\bf 85}, 4418
(2000), where results for were presented. The extension up to N=16 is
possible when one defines for each N a specially chosen set of observables. We
also present results concerning the critical detectors efficiency beyond which
a valid test of local realism for entangled quNits is possible.Comment: 5 pages, 3 ps picture
Spinocerebellar ataxia type 17: Report of a family with reduced penetrance of an unstable Gln(49 )TBP allele, haplotype analysis supporting a founder effect for unstable alleles and comparative analysis of SCA17 genotypes
BACKGROUND: Spinocerebellar ataxia type 17 (SCA17), a neurodegenerative disorder in man, is caused by an expanded polymorphic polyglutamine-encoding trinucleotide repeat in the gene for TATA-box binding protein (TBP), a main transcription factor. Observed pathogenic expansions ranged from 43 – 63 glutamine (Gln) codons (Gln(43–63)). Reduced penetrance is known for Gln(43–48 )alleles. In the vast majority of families with SCA17 an expanded CAG repeat interrupted by a CAA CAG CAA element is inherited stably. RESULTS: Here, we report the first pedigree with a Gln(49 )allele that is a) not interrupted, b) unstable upon transmission, and c) associated with reduced penetrance or very late age of onset. The 76-year-old father of two SCA17 patients carries the Gln(49 )TBP allele but presents without obvious neurological symptoms. His children with Gln(53 )and Gln(52 )developed ataxia at the age of 41 and 50. Haplotype analysis of this and a second family both with uninterrupted expanded and unstable pathological SCA17 alleles revealed a common core genotype not present in the interrupted expansion of an unrelated SCA17 patient. Review of the literature did not present instability in SCA17 families with expanded alleles interrupted by the CAA CAG CAA element. CONCLUSION: The presence of a Gln(49 )SCA17 allele in an asymptomatic 76-year-old male reams the discussion of reduced penetrance and genotypes producing very late disease onset. In SCA17, uninterrupted expanded alleles of TBP are associated with repeat instability and a common founder haplotype. This suggests for uninterrupted expanded alleles a mutation mechanism and some clinical genetic features distinct from those alleles interrupted by a CAA CAG CAA element
Sensitivity of LHC experiments to exotic highly ionising particles
The experiments at the Large Hadron Collider (LHC) are able to discover or
set limits on the production of exotic particles with TeV-scale masses
possessing values of electric and/or magnetic charge such that they behave as
highly ionising particles (HIPs). In this paper the sensitivity of the LHC
experiments to HIP production is discussed in detail. It is shown that a number
of different detection methods are required to investigate as fully as possible
the charge-mass range. These include direct detection as the HIPs pass through
either passive or active detectors and, in the case of magnetically charged
objects, the so-called induction method with which magnetic monopoles which
stop in accelerator and detector material could be observed. The benefit of
using complementary approaches to HIP detection is discussed.Comment: 20 pages, 52 figure
The TanDEM-X Mission - Towards a Global Digital Elevation Model: Four Years of Experience in Large Volume Data Management
This article provides a short overview about the TanDEM-X
mission, its objectives and the payload ground segment
(PGS) based on data management, processing systems and
long term archive. Due to the large data volume of the
acquired and processed products a main challenge in the
operation of the PGS is to handle the required data
throughput, which is a new dimension for the DLR PGS. To
achieve this requirement, several solutions were developed
and coordinated. Some of them were more technical nature
whereas others optimized the workflows