180 research outputs found
Dilepton Production in and Colliders
In an collider, a striking signature for a dilepton gauge boson is
\ep \ ; this cross-section is calculated by using the helicity amplitude
technique. At HERA, with center-of-mass energy , a dilepton
mass above is inaccessible but at LEPII-LHC, with a center-of-mass
energy , masses up to 650 GeV can be discovered. In an
collider, the signature is \ee \ . The cross-sections of this process
are also calculated for the center-of-mass energies and
.Comment: 16 pages, 3 figures (not included), IFP-428-UN
Down for the Count? Getting Reference Counting Back in the Ring
Reference counting and tracing are the two fundamental approaches that have underpinned garbage collection since 1960. However, despite some compelling advantages, reference counting is almost completely ignored in implementations of high performance systems today. In this paper we take a detailed look at reference counting to understand its behavior and to improve its performance. We identify key design choices for reference counting and analyze how the behavior of a wide range of benchmarks might affect design decisions. As far as we are aware, this is the first such quantitative study of reference counting. We use insights gleaned from this analysis to introduce a number of optimizations that significantly improve the performance of reference counting. We find that an existing modern implementation of reference counting has an average 30% overhead compared to tracing, and that in combination, our optimizations are able to completely eliminate that overhead. This brings the performance of reference counting on par with that of a well tuned mark-sweep collector. We keep our in-depth analysis of reference counting as general as possible so that it may be useful to other garbage collector implementers. Our finding that reference counting can be made directly competitive with well tuned mark-sweep should shake the community's prejudices about reference counting and perhaps open new opportunities for exploiting reference counting's strengths, such as localization and immediacy of reclamation
1999-2000 Alumni Concert
This concert is dedicated to the memory of Nicolas Larin (B.M. 1995)
-- mixing and oblique corrections in an model
A global fit for experiments is included in this revised version.Comment: IFP-460-UNC, TRI-PP-93-11, 20 pages, 2 figures are appende
Prognostic significance of high GFI1 expression in AML of normal karyotype and its association with a FLT3-ITD signature
Abstract Growth Factor Independence 1 (GFI1) is a transcriptional repressor that plays a critical role during both myeloid and lymphoid haematopoietic lineage commitment. Several studies have demonstrated the involvement of GFI1 in haematological malignancies and have suggested that low expression of GFI1 is a negative indicator of disease progression for both myelodysplastic syndromes (MDS) and acute myeloid leukaemia (AML). In this study, we have stratified AML patients into those defined as having a normal karyotype (CN-AML). Unlike the overall pattern in AML, those patients with CN-AML have a poorer survival rate when GFI1 expression is high. In this group, high GFI1 expression is paralleled by higher FLT3 expression, and, even when the FLT3 gene is not mutated, exhibit a FLT3-ITD signature of gene expression. Knock-down of GFI1 expression in the human AML Fujioka cell line led to a decrease in the level of FLT3 RNA and protein and to the down regulation of FLT3-ITD signature genes, thus linking two major prognostic indicators for AML
The 331 model with right-handed neutrinos
We explore some more consequences of the electroweak
model with right-handed neutrinos. By introducing the mixing angle
, the {\it exact} physical eigenstates for neutral gauge bosons are
obtained. Because of the mixing, there is a modification to the coupling
proportional to . The data from the -decay allows us to fix the
limit for as . >From the neutrino
neutral current scatterings, we estimate a bound for the new neutral gauge
boson mass in the range 300 GeV, and from symmetry-breaking hierarchy a
bound for the new charged and neutral (non-Hermitian) gauge bosons are obtained.Comment: Slight changes in section 5, Latex, 16 page
Gauge coupling unification with large extra dimensions
We make a detailed study of the unification of gauge couplings in the MSSM
with large extra dimensions. We find some scenarios where unification can be
achieved (with the strong coupling constant at the Z mass within one standard
deviation of the experimental value) with both the compactification scale and
the SUSY breaking scale in the few TeV range. No enlargement of the gauge group
or particle content is needed. One particularly interesting scenario is when
the SUSY breaking scale is larger than the compactification scale, but both are
small enough to be probed at the CERN LHC. Unification in two scales scenarios
is also investigated and found to give results within the LHC.Comment: 17 pages, 3 figures, some discussions added, few additional
references included. Version to appear in Phys. Rev.
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