151 research outputs found
Dimension-six CP-conserving operators of the third-family quarks and their effects on collider observables
We list all possible dimension-six CP-conserving invariant operators involving the third-family quarks which
could be generated by new physics at a higher scale. Expressions for these
operators after electroweak gauge symmetry breaking and the induced effective
couplings , and are
presented. Analytic expressions for the tree level contributions of all these
operators to the observables and at LEP I,
and at LEP II,
and at the NLC, as well as
at the Tevatron upgrade, are provided.
The effects of these operators on different electroweak observables are
discussed and numerical examples presented. Numerical analyses show that in the
coupling region allowed by and at LEP I, some of the new
physics operators can still have significant contributions at LEP II, the
Tevatron and the NLC.Comment: 25 page
Probing Topcolor-Assisted Technicolor from Top-Charm Associated Production at LHC
We propose to probe the topcolor-assisted technicolor (TC2) model from the
top-charm associated productions at the LHC, which are highly suppressed in the
Standard Model. Due to the flavor-changing couplings of the top quark with the
scalars (top-pions and top-Higgs) in TC2 model, the top-charm associated
productions can occur via both the s-channel and t-channel parton processes by
exchanging a scalar field at the LHC. We examined these processes through Monte
Carlo simulation and found that they can reach the observable level at the LHC
in quite a large part of the parameter space of the TC2 model.Comment: Version to appear in PRD (Rapid Communication
Single Top Quark Production via FCNC Couplings at Hadron Colliders
We calculate single top-quark production at hadron colliders via the
chromo-magnetic flavor-changing neutral current couplings and . We find that the strength for the anomalous ()
coupling may be probed to () at the Tevatron with of data and
() at the LHC with of data. The two couplings may be
distinguished by a comparision of the single top signal with the direct top and
top decay signals for these couplings.Comment: 18 pages, 6 figures, 3 table
Ep-CAM expression in squamous cell carcinoma of the esophagus: a potential therapeutic target and prognostic marker
BACKGROUND: To evaluate the expression and test the clinical significance of the epithelial cellular adhesion molecule (Ep-CAM) in esophageal squamous cell carcinoma (SCC) to check the suitability of esophageal SCC patients for Ep-CAM directed targeted therapies. METHODS: The Ep-CAM expression was immunohistochemically investigated in 70 primary esophageal SCCs using the monoclonal antibody Ber-EP4. For the interpretation of the staining results, we used a standardized scoring system ranging from 0 to 3+. The survival analysis was calculated from 53 patients without distant metastasis, with R0 resection and at least 2 months of clinical follow-up. RESULTS: Ep-CAM neo-expression was observed in 79% of the tumors with three expression levels, 1+ (26%), 2+ (11%) and 3+ (41%). Heterogeneous expression was observed at all expression levels. Interestingly, tumors with 3+ Ep-CAM expression conferred a significantly decreased median relapse-free survival period (log rank, p = 0.0001) and median overall survival (log rank, p = 0.0003). Multivariate survival analysis disclosed Ep-CAM 3+ expression as independent prognostic factor. CONCLUSION: Our results suggest Ep-CAM as an attractive molecule for targeted therapy in esophageal SCC. Considering the discontenting results of the current adjuvant concepts for esophageal SCC patients, Ep-CAM might provide a promising target for an adjuvant immunotherapeutic intervention
Stop and Sbottom Searches in Run II of the Fermilab Tevatron
We estimate the Tevatron Run II potential for top and bottom squark searches.
We find an impressive reach in several of the possible discovery channels. We
also study some new channels which may arise in non-conventional supersymmetry
models. In each case we rely on a detailed Monte Carlo simulation of the
collider events and the CDF detector performance in Run I.Comment: 30 pages, LaTeX, 10 figure
Single top production at the LHC as a probe of R parity violation
We investigate the potential of the LHC to probe the R parity violating
couplings involving the third generation by considering single top production.
This study is based on particle level event generation for both signal and
background, interfaced to a simplified simulation of the ATLAS detector.Comment: 11 pages, 5 figures, 5 tables (LaTeX, style revtex), few references
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Homologous and heterologous desensitization of guanylyl cyclase-B signaling in GH3 somatolactotropes
The guanylyl cyclases, GC-A and GC-B, are selective receptors for atrial and C-type natriuretic peptides (ANP and CNP, respectively). In the anterior pituitary, CNP and GC-B are major regulators of cGMP production in gonadotropes and yet mouse models of disrupted CNP and GC-B indicate a potential role in growth hormone secretion. In the current study, we investigate the molecular and pharmacological properties of the CNP/GC-B system in somatotrope lineage cells. Primary rat pituitary and GH3 somatolactotropes expressed functional GC-A and GC-B receptors that had similar EC50 properties in terms of cGMP production. Interestingly, GC-B signaling underwent rapid homologous desensitization in a protein phosphatase 2A (PP2A)-dependent manner. Chronic exposure to either CNP or ANP caused a significant down-regulation of both GC-A- and GC-B-dependent cGMP accumulation in a ligand-specific manner. However, this down-regulation was not accompanied by alterations in the sub-cellular localization of these receptors. Heterologous desensitization of GC-B signaling occurred in GH3 cells following exposure to either sphingosine-1-phosphate or thyrotrophin-releasing hormone (TRH). This heterologous desensitization was protein kinase C (PKC)-dependent, as pre-treatment with GF109203X prevented the effect of TRH on CNP/GC-B signaling. Collectively, these data indicate common and distinct properties of particulate guanylyl cyclase receptors in somatotropes and reveal that independent mechanisms of homologous and heterologous desensitization occur involving either PP2A or PKC. Guanylyl cyclase receptors thus represent potential novel therapeutic targets for treating growth-hormone-associated disorders
Cystic Echinococcosis: Chronic, Complex, and Still Neglected
Cystic echinococcosis is a most clinically neglected
parasitic disease that urgently needs attention.
A valuable tool for diagnosing,
staging, and following up patients, ultrasound,
is readily available. Four management
procedures, surgery, percutaneous
sterilization techniques, anti-parasitic
treatment, and watch & wait, have
‘‘evolved’’ over decades, and been recently
summarized, but without adequate
comparative evaluation of efficacy, effectiveness,
rate of adverse events, relapse
rates, and cost. Clinical decision making is
on even shakier ground for extrahepatic
and extrapulmonary locations, which are
rarer and numbers needed to build
comparative trials hard to come by. There
is an obligation to put at least what we
have on an appropriate evidence base by
conducting comparative clinical trials at
the scale and quality that allow answering
these important questions. As one of the
expected results, clear criteria for the
watch & wait option alone might already
save a substantial proportion of patients
from unnecessary interventions and save
health services money. Difficult chronic
diseases clustering in poor rural areas need
intelligent, creative approaches, and this
one urgently needs operational research
incorporating the particularities of resource-
poor settings into consideration
Single Top Production as a Window to Physics Beyond the Standard Model
Production of single top quarks at a high energy hadron collider is studied
as a means to identify physics beyond the standard model related to the
electroweak symmetry breaking. The sensitivity of the -channel mode,
the -channel -gluon fusion mode, and the \tw mode to various possible
forms of new physics is assessed, and it is found that the three modes are
sensitive to different forms of new physics, indicating that they provide
complimentary information about the properties of the top quark. Polarization
observables are also considered, and found to provide potentially useful
information about the structure of the interactions of top.Comment: References added and minor discussion improvements; results
unchanged; Version to be published in PR
Supersymmetric effects in top quark decay into polarized W-boson
We investigate the one-loop supersymmetric QCD (SUSY-QCD) and electroweak
(SUSY-EW) corrections to the top quark decay into a b-quark and a longitudinal
or transverse W-boson. The corrections are presented in terms of the
longitudinal ratio \Gamma(t-->W_L b)/\Gamma(t--> W b) and the transverse ratio
\Gamma(t-->W_- b)/\Gamma(t--> W b). In most of the parameter space, both
SUSY-QCD and SUSY-EW corrections to these ratios are found to be less than 1%
in magnitude and they tend to have opposite signs. The corrections to the total
width \Gamma(t-->W b) are also presented for comparison with the existing
results in the literature. We find that our SUSY-EW corrections to the total
width differ significantly from previous studies: the previous studies give a
large correction of more than 10% in magnitude for a large part of the
parameter space while our results reach only few percent at most.Comment: Version in PRD (explanation and refs added
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