379 research outputs found
A noninvasive multi-analyte diagnostic assay: Combining protein and DNA markers to stratify bladder cancer patients
Purpose: The authors recently reported the development of a noninvasive diagnostic assay using urinary matrix metalloproteinases (MMPs) as monitors of disease-free status and bladder cancer in high-risk populations. Using an approach called clinical intervention determining diagnostic (CIDD), they identified with high confidence those patients who could be excluded from additional intervention. To maximize performance, MMPs were combined with DNAbased markers and CIDD was applied to a population of patients undergoing monitoring for recurrence. Patients and methods: Urine samples were obtained from 323 patients, 48 of whom had a recurrence and 275 of whom did not have cancer upon cytoscopic evaluation. Twist1 and Nid2 methylation status was determined using methylation-specific polymerase chain reaction, FGFR3 mutational status by quantitative PCR, and MMP levels by enzyme-linked immunosorbent assay. Results: Using a combination of these DNA and protein markers, the authors identified with high confidence (97% negative predicted value) those patients who do not have cancer. Cutoffs were adjusted such that at 92% sensitivity, 51% of disease-free patients might be triaged from receiving further tests. Conclusion: The multi-analyte diagnostic readout assay described here is the first to combine protein and DNA biomarkers into one assay for optimal clinical performance. Using this approach, the detection of FGFR3 mutations and Twist1 and Nid2 methylation in the urine of patients undergoing bladder cancer recurrence screening increase the sensitivity and negative predictive value at an established MMP protein cutoff. This noninvasive urinary diagnostic assay could lead to the more efficient triage of patients undergoing recurrence monitoring
The Potts Fully Frustrated model: Thermodynamics, percolation and dynamics in 2 dimensions
We consider a Potts model diluted by fully frustrated Ising spins. The model
corresponds to a fully frustrated Potts model with variables having an integer
absolute value and a sign. This model presents precursor phenomena of a glass
transition in the high-temperature region. We show that the onset of these
phenomena can be related to a thermodynamic transition. Furthermore this
transition can be mapped onto a percolation transition. We numerically study
the phase diagram in 2 dimensions (2D) for this model with frustration and {\em
without} disorder and we compare it to the phase diagram of the model with
frustration {\em and} disorder and of the ferromagnetic model.
Introducing a parameter that connects the three models, we generalize the exact
expression of the ferromagnetic Potts transition temperature in 2D to the other
cases. Finally, we estimate the dynamic critical exponents related to the Potts
order parameter and to the energy.Comment: 10 pages, 10 figures, new result
Parity Violation in Proton-Proton Scattering
Measurements of parity-violating longitudinal analyzing powers (normalized
asymmetries) in polarized proton-proton scattering provide a unique window on
the interplay between the weak and strong interactions between and within
hadrons. Several new proton-proton parity violation experiments are presently
either being performed or are being prepared for execution in the near future:
at TRIUMF at 221 MeV and 450 MeV and at COSY (Kernforschungsanlage Juelich) at
230 MeV and near 1.3 GeV. These experiments are intended to provide stringent
constraints on the set of six effective weak meson-nucleon coupling constants,
which characterize the weak interaction between hadrons in the energy domain
where meson exchange models provide an appropriate description. The 221 MeV is
unique in that it selects a single transition amplitude (3P2-1D2) and
consequently constrains the weak meson-nucleon coupling constant h_rho{pp}. The
TRIUMF 221 MeV proton-proton parity violation experiment is described in some
detail. A preliminary result for the longitudinal analyzing power is Az = (1.1
+/-0.4 +/-0.4) x 10^-7. Further proton-proton parity violation experiments are
commented on. The anomaly at 6 GeV/c requires that a new multi-GeV
proton-proton parity violation experiment be performed.Comment: 13 Pages LaTeX, 5 PostScript figures, uses espcrc1.sty. Invited talk
at QULEN97, International Conference on Quark Lepton Nuclear Physics --
Nonperturbative QCD Hadron Physics & Electroweak Nuclear Processes --, Osaka,
Japan May 20--23, 199
Searching for a Cosmological Preferred Axis: Union2 Data Analysis and Comparison with Other Probes
We review, compare and extend recent studies searching for evidence for a
preferred cosmological axis. We start from the Union2 SnIa dataset and use the
hemisphere comparison method to search for a preferred axis in the data. We
find that the hemisphere of maximum accelerating expansion rate is in the
direction (\omm=0.19) while the hemisphere of
minimum acceleration is in the opposite direction
(\omm=0.30). The level of anisotropy is described by the normalized
difference of the best fit values of \omm between the two hemispheres in the
context of \lcdm fits. We find a maximum anisotropy level in the Union2 data of
\frac{\Delta \ommax}{\bomm}=0.43\pm 0.06. Such a level does not necessarily
correspond to statistically significant anisotropy because it is reproduced by
about of simulated isotropic data mimicking the best fit Union2 dataset.
However, when combined with the axes directions of other cosmological
observations (bulk velocity flow axis, three axes of CMB low multipole moments
and quasar optical polarization alignment axis), the statistical evidence for a
cosmological anisotropy increases dramatically. We estimate the probability
that the above independent six axes directions would be so close in the sky to
be less than . Thus either the relative coincidence of these six axes is a
very large statistical fluctuation or there is an underlying physical or
systematic reason that leads to their correlation.Comment: 10 pages, 7 figures. Accepted in JCAP (to appear). Extended analysis
with redshift tomography of SnIa, included errorbars and increased number of
axes. The Mathematica 7 files with the data used for the production of the
figures along with a Powerpoint file with additional figures may be
downloaded from http://leandros.physics.uoi.gr/anisotrop
Parity nonconserving cold neutron-parahydrogen interactions
Three pion dominated observables of the parity nonconserving interactions
between the cold neutrons and parahydrogen are calculated. The transversely
polarized neutron spin rotation, unpolarized neutron longitudinal polarization,
and photon-asymmetry of the radiative polarized neutron capture are considered.
For the numerical evaluation of the observables, the strong interactions are
taken into account by the Reid93 potential and the parity nonconserving
interactions by the DDH model along with the two-pion exchange.Comment: 17 pages, 2 figure
Mutation of Ser172 in Yeast β Tubulin Induces Defects in Microtubule Dynamics and Cell Division
Ser172 of β tubulin is an important residue that is mutated in a human brain disease and phosphorylated by the cyclin-dependent kinase Cdk1 in mammalian cells. To examine the role of this residue, we used the yeast S. cerevisiae as a model and produced two different mutations (S172A and S172E) of the conserved Ser172 in the yeast β tubulin Tub2p. The two mutants showed impaired cell growth on benomyl-containing medium and at cold temperatures, altered microtubule (MT) dynamics, and altered nucleus positioning and segregation. When cytoplasmic MT effectors Dyn1p or Kar9p were deleted in S172A and S172E mutants, cells were viable but presented increased ploidy. Furthermore, the two β tubulin mutations exhibited synthetic lethal interactions with Bik1p, Bim1p or Kar3p, which are effectors of cytoplasmic and spindle MTs. In the absence of Mad2p-dependent spindle checkpoint, both mutations are deleterious. These findings show the importance of Ser172 for the correct function of both cytoplasmic and spindle MTs and for normal cell division
Observation of exclusive DVCS in polarized electron beam asymmetry measurements
We report the first results of the beam spin asymmetry measured in the
reaction e + p -> e + p + gamma at a beam energy of 4.25 GeV. A large asymmetry
with a sin(phi) modulation is observed, as predicted for the interference term
of Deeply Virtual Compton Scattering and the Bethe-Heitler process. The
amplitude of this modulation is alpha = 0.202 +/- 0.028. In leading-order and
leading-twist pQCD, the alpha is directly proportional to the imaginary part of
the DVCS amplitude.Comment: 6 pages, 5 figure
A Bayesian analysis of pentaquark signals from CLAS data
We examine the results of two measurements by the CLAS collaboration, one of
which claimed evidence for a pentaquark, whilst the other found no
such evidence. The unique feature of these two experiments was that they were
performed with the same experimental setup. Using a Bayesian analysis we find
that the results of the two experiments are in fact compatible with each other,
but that the first measurement did not contain sufficient information to
determine unambiguously the existence of a . Further, we suggest a
means by which the existence of a new candidate particle can be tested in a
rigorous manner.Comment: 5 pages, 3 figure
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