767 research outputs found
Study of the finite temperature transition in 3-flavor QCD using the R and RHMC algorithms
We study the finite temperature transition in QCD with three flavors of equal
masses using the R and RHMC algorithm on lattices with temporal extent
N_{\tau}=4 and 6. For the transition temperature in the continuum limit we find
r_0 T_c=0.429(8) for the light pseudo-scalar mass corresponding to the end
point of the 1st order transition region. When comparing the results obtained
with the R and RHMC algorithms for p4fat3 action we see no significant
step-size errors down to a lightest pseudo-scalar mass of m_{ps} r_0=0.4.Comment: 13 pages, RevTeX, 10 figure
The transition temperature in QCD
We present a detailed calculation of the transition temperature in QCD with
two light and one heavier (strange) quark mass on lattices with temporal extent
N_t =4 and 6. Calculations with improved staggered fermions have been performed
for various light to strange quark mass ratios in the range, 0.05 <= m_l/m_s <=
0.5, and with a strange quark mass fixed close to its physical value. From a
combined extrapolation to the chiral (m_l -> 0) and continuum (aT = 1/N_t -> 0)
limits we find for the transition temperature at the physical point T_c r_0 =
0.457(7) where the scale is set by the Sommer-scale parameter r_0 defined as
the distance in the static quark potential at which the slope takes on the
value, (dV_qq(r)/dr)_r=r_0 = 1.65/r_0^2. Using the currently best known value
for r_0 this translates to a transition temperature T_c = 192(7)(4)MeV. The
transition temperature in the chiral limit is about 3% smaller. We discuss
current ambiguities in the determination of T_c in physical units and also
comment on the universal scaling behavior of thermodynamic quantities in the
chiral limit.Comment: 18 pages, 14 EPS figures, replaced wrong entries in column 7 of Table
A.
Spectral Density Study of the SU(3) Deconfining Phase Transition
We present spectral density reweighting techniques adapted to the analysis of
a time series of data with a continuous range of allowed values. In a first
application we analyze action and Polyakov line data from a Monte Carlo
simulation on lattices for the SU(3) deconfining phase
transition. We calculate partition function zeros, as well as maxima of the
specific heat and of the order parameter susceptibility. Details and warnings
are given concerning i) autocorrelations in computer time and ii) a reliable
extraction of partition function zeros. The finite size scaling analysis of
these data leads to precise results for the critical couplings , for
the critical exponent and for the latent heat . In both
cases ( and 4), the first order nature of the transition is
substantiated
Enhancement-mode PEDOT:PSS organic electrochemical transistors using molecular de-doping
Organic electrochemical transistors (OECTs) show great promise for flexible, low-cost, and low-voltage sensors for aqueous solutions. The majority of OECT devices are made using the polymer blend poly(ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), in which PEDOT is intrinsically doped due to inclusion of PSS. Because of this intrinsic doping, PEDOT:PSS OECTs generally operate in depletion mode, which results in a higher power consumption and limits stability. Here, a straightforward method to de-dope PEDOT:PSS using commercially available amine-based molecular de-dopants to achieve stable enhancement-mode OECTs is presented. The enhancement-mode OECTs show mobilities near that of pristine PEDOT:PSS (â2 cm2 Vâ1 sâ1) with stable operation over 1000 on/off cycles. The electron and proton exchange among PEDOT, PSS, and the molecular de-dopants are characterized to reveal the underlying chemical mechanism of the threshold voltage shift to negative voltages. Finally, the effect of the de-doping on the microstructure of the spin-cast PEDOT:PSS films is investigated.</p
Non-muscle-invasive bladder cancer surveillance for which cystoscopy is partly replaced by microsatellite analysis of urine: a cost-effective alternative?
OBJECTIVE To determine how good microsatellite analysis (MA) markers in voided urine samples should be to make a surveillance procedure cost-effective in which cystoscopy is partly replaced by MA for patients with non-muscle-invasive urothelial carcinoma (NMI-UC). PATIENTS AND METHODS We constructed a semi-Markov model with a time horizon of 2 years, and a man aged 65 years as reference case. Data were used from a randomized trial (including 448 patients with NMI-UC from 10 hospitals), and from other data sources. The costs and effects (probability of being in a specific health state) were compared for two surveillance strategies: (i) cystos
The relationships between internal and external threat and right-wing attitudes: A three-wave longitudinal study
The interplay between threat and right-wing attitudes has received much research attention, but its longitudinal relationship has hardly been investigated. In this study, we investigated the longitudinal relationships between internal and external threat and right-wing attitudes using a cross-lagged design at three different time points in a large nationally representative sample (N = 800). We found evidence for bidirectional relationships. Higher levels of external threat were related to higher levels of Right-Wing Authoritarianism and to both the egalitarianism and dominance dimensions of Social Dominance Orientation at a later point in time. Conversely, higher levels of RWA were also related to increased perception of external threat later in time. Internal threat did not yield significant direct or indirect longitudinal relationships with right-wing attitudes. Theoretical and practical implications of these longitudinal effects are discussed
The QCD Equation of State with almost Physical Quark Masses
We present results on the equation of state in QCD with two light quark
flavors and a heavier strange quark. Calculations with improved staggered
fermions have been performed on lattices with temporal extent Nt =4 and 6 on a
line of constant physics with almost physical quark mass values; the pion mass
is about 220 MeV, and the strange quark mass is adjusted to its physical value.
High statistics results on large lattices are obtained for bulk thermodynamic
observables, i.e. pressure, energy and entropy density, at vanishing quark
chemical potential for a wide range of temperatures, 140 MeV < T < 800 MeV. We
present a detailed discussion of finite cut-off effects which become
particularly significant for temperatures larger than about twice the
transition temperature. At these high temperatures we also performed
calculations of the trace anomaly on lattices with temporal extent Nt=8.
Furthermore, we have performed an extensive analysis of zero temperature
observables including the light and strange quark condensates and the static
quark potential at zero temperature. These are used to set the temperature
scale for thermodynamic observables and to calculate renormalized observables
that are sensitive to deconfinement and chiral symmetry restoration and become
order parameters in the infinite and zero quark mass limits, respectively.Comment: 22 pages, 17 EPS-figures; revised version, updated references, data
added in Tab.1, several smaller change
Maximal Non-Abelian Gauges and Topology of Gauge Orbit Space
We introduce two maximal non-abelian gauge fixing conditions on the space of
gauge orbits M for gauge theories over spaces with dimensions d < 3. The gauge
fixings are complete in the sense that describe an open dense set M_0 of the
space of gauge orbits M and select one and only one gauge field per gauge orbit
in M_0. There are not Gribov copies or ambiguities in these gauges. M_0 is a
contractible manifold with trivial topology. The set of gauge orbits which are
not described by the gauge conditions M \ M_0 is the boundary of M_0 and
encodes all non-trivial topological properties of the space of gauge orbits.
The gauge fields configurations of this boundary M \ M_0 can be explicitly
identified with non-abelian monopoles and they are shown to play a very
relevant role in the non-perturbative behaviour of gauge theories in one, two
and three space dimensions. It is conjectured that their role is also crucial
for quark confinement in 3+1 dimensional gauge theories.Comment: 31 pages, harvmac, 1 figur
Collagen II Is Essential for the Removal of the Notochord and the Formation of Intervertebral Discs
Collagen II is a fibril-forming collagen that is mainly expressed in cartilage. Collagen IIâdeficient mice produce structurally abnormal cartilage that lacks growth plates in long bones, and as a result these mice develop a skeleton without endochondral bone formation. Here, we report that Col2a1-null mice are unable to dismantle the notochord. This defect is associated with the inability to develop intervertebral discs (IVDs). During normal embryogenesis, the nucleus pulposus of future IVDs forms from regional expansion of the notochord, which is simultaneously dismantled in the region of the developing vertebral bodies. However, in Col2a1-null mice, the notochord is not removed in the vertebral bodies and persists as a rod-like structure until birth. It has been suggested that this regional notochordal degeneration results from changes in cell death and proliferation. Our experiments with wild-type mice showed that differential proliferation and apoptosis play no role in notochordal reorganization. An alternative hypothesis is that the cartilage matrix exerts mechanical forces that induce notochord removal. Several of our findings support this hypothesis. Immunohistological analyses, in situ hybridization, and biochemical analyses demonstrate that collagens I and III are ectopically expressed in Col2a1-null cartilage. Assembly of the abnormal collagens into a mature insoluble matrix is retarded and collagen fibrils are sparse, disorganized, and irregular. We propose that this disorganized abnormal cartilage collagen matrix is structurally weakened and is unable to constrain proteoglycan-induced osmotic swelling pressure. The accumulation of fluid leads to tissue enlargement and a reduction in the internal swelling pressure. These changes may be responsible for the abnormal notochord removal in Col2a1-null mice
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