894 research outputs found
The directed flow maximum near c_s=0
We investigate the excitation function of quark-gluon plasma formation and of
directed in-plane flow of nucleons in the energy range of the BNL-AGS and for
the E(Lab)=40AGeV Pb+Pb collisions performed recently at the CERN-SPS. We
employ the three-fluid model with dynamical unification of kinetically
equilibrated fluid elements. Within our model with first-order phase transition
at high density, droplets of QGP coexisting with hadronic matter are produced
already at BNL-AGS energies, E(Lab)=10AGeV. A substantial decrease of the
isentropic velocity of sound, however, requires higher energies, E(Lab)=40AGeV.
We show the effect on the flow of nucleons in the reaction plane. According to
our model calculations, kinematic requirements and EoS effects work
hand-in-hand at E(Lab)=40AGeV to allow the observation of the dropping velocity
of sound via an increase of the directed flow around midrapidity as compared to
top BNL-AGS energy.Comment: 10 pages, 4 figures; plot of p(e) at various specific entropies shows
why mixed phase is not soft at AGS energ
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Effect of Build Parameters and Build Geometries on Residual Microstructures and Mechanical Properties of Ti-6Al-4V Components Built by Electron Beam Melting (EBM)
In this study, involving additive manufacturing (AM) using electron beam melting (EBM), we
have examined build defects which result from beam tripping, porosities (including unmelted or
unsintered zones) due to excursions from optimal build parameters (especially variations in melt
scan beam current and scan speed), and gas bubbles trapped in atomized Ti-6Al-4V starting
powder as well as recycled powder, and retained in the build. At optimized build conditions we
have also examined microstructure-mechanical property (hardness, tensile strength, and
elongation) variations for multiple rake building and multiple melt scans using optical
metallography and scanning and transmission electron microscopy (SEM and TEM). These
build variances cause cooling rate variances which promote α-phase growth and variations in
dislocation density, as well as α-to-α' (martensite) phase changes, all of which produce some
degree of mechanical property variations. These features (especially α-to-α' phase changes) are
notable on comparing solid builds in comparison with a variety of mesh arrays where strut
dimension and build-element complexities alter the cooling rates in a significant way. We
illustrate these microstructure variations with corresponding variations in microindentation
hardness measurements made directly on fine mesh (strut) structures. Finally, we have examined
Ti-6Al-4V powder chemistries and solid build chemistries which for single-pass melt scans at
optimized build conditions are shown to be relatively constant up to 40 cycles of powder reuse
with the exception of Al content which was reduced by 10 to 15% in solid builds at optimized
conditions. However, Al loss in solid builds approached 25% for multiple (2 and 3) melt scans,
while no changes in Ar gas-bubble density were observed with changes in α-phase (grain) width
which increased from 3 ”m for a single melt scan to 4.5 and 6 ”m for 2 and 3 melt scans,
respectively. Corresponding Rockwell C-scale (HRC) hardness varied from 37, 36, and 35,
respectively; with ultimate tensile strengths exceeding 1.2 GPa at elongations of 12% or higher
for this melt scan sequence.Mechanical Engineerin
The ÎŽN formula is the dynamical renormalization group
We derive the 'separate universe' method for the inflationary bispectrum,
beginning directly from a field-theory calculation. We work to tree-level in
quantum effects but to all orders in the slow-roll expansion, with masses
accommodated perturbatively. Our method provides a systematic basis to account
for novel sources of time-dependence in inflationary correlation functions, and
has immediate applications. First, we use our result to obtain the correct
matching prescription between the 'quantum' and 'classical' parts of the
separate universe computation. Second, we elaborate on the application of this
method in situations where its validity is not clear. As a by-product of our
calculation we give the leading slow-roll corrections to the three-point
function of field fluctuations on spatially flat hypersurfaces in a canonical,
multiple-field model.Comment: v1: 33 pages, plus appendix and references; 5 figures. v2:
typographical typos fixed, minor changes to the main text and abstract,
reference added; matches version published in JCA
Excluded Volume Effects in the Quark Meson Coupling Model
Excluded volume effects are incorporated in the quark meson coupling model to
take into account in a phenomenological way the hard core repulsion of the
nuclear force. The formalism employed is thermodynamically consistent and does
not violate causality. The effects of the excluded volume on in-medium nucleon
properties and the nuclear matter equation of state are investigated as a
function of the size of the hard core. It is found that in-medium nucleon
properties are not altered significantly by the excluded volume, even for large
hard core radii, and the equation of state becomes stiffer as the size of the
hard core increases.Comment: 14 pages, revtex, 6 figure
Sea lions develop human-like vernix caseosa delivering branched fats and squalene to the GI tract
Vernix caseosa, the white waxy coating found on newborn human skin, is thought to be a uniquely human substance. Its signature characteristic is exceptional richness in saturated branched chain fatty acids (BCFA) and squalene. Vernix particles sloughed from the skin suspended in amniotic fluid are swallowed by the human fetus, depositing BCFA/squalene throughout the gastrointestinal (GI) tract, thereby establishing a unique microbial niche that influences development of nascent microbiota. Here we show that late-term California sea lion (Zalophus californianus) fetuses have true vernix caseosa, delivering BCFA and squalene to the fetal GI tract thereby recapitulating the human fetal gut microbial niche. These are the first data demonstrating the production of true vernix caseosa in a species other than Homo sapiens. Its presence in a marine mammal supports the hypothesis of an aquatic habituation period in the evolution of modern humans
Super-Hubble de Sitter Fluctuations and the Dynamical RG
Perturbative corrections to correlation functions for interacting theories in
de Sitter spacetime often grow secularly with time, due to the properties of
fluctuations on super-Hubble scales. This growth can lead to a breakdown of
perturbation theory at late times. We argue that Dynamical Renormalization
Group (DRG) techniques provide a convenient framework for interpreting and
resumming these secularly growing terms. In the case of a massless scalar field
in de Sitter with quartic self-interaction, the resummed result is also less
singular in the infrared, in precisely the manner expected if a dynamical mass
is generated. We compare this improved infrared behavior with large-N
expansions when applicable.Comment: 33 pages, 4 figure
Equation of state for Universe from similarity symmetries
In this paper we proposed to use the group of analysis of symmetries of the
dynamical system to describe the evolution of the Universe. This methods is
used in searching for the unknown equation of state. It is shown that group of
symmetries enforce the form of the equation of state for noninteracting scaling
multifluids. We showed that symmetries give rise the equation of state in the
form and energy density
, which
is commonly used in cosmology. The FRW model filled with scaling fluid (called
homological) is confronted with the observations of distant type Ia supernovae.
We found the class of model parameters admissible by the statistical analysis
of SNIa data. We showed that the model with scaling fluid fits well to
supernovae data. We found that and (), which can correspond to (hyper) phantom fluid, and to a
high density universe. However if we assume prior that
then the favoured model is close to concordance
CDM model. Our results predict that in the considered model with
scaling fluids distant type Ia supernovae should be brighter than in
CDM model, while intermediate distant SNIa should be fainter than in
CDM model. We also investigate whether the model with scaling fluid is
actually preferred by data over CDM model. As a result we find from
the Akaike model selection criterion prefers the model with noninteracting
scaling fluid.Comment: accepted for publication versio
Large slow-roll corrections to the bispectrum of noncanonical inflation
Nongaussian statistics are a powerful discriminant between inflationary
models, particularly those with noncanonical kinetic terms. Focusing on
theories where the Lagrangian is an arbitrary Lorentz-invariant function of a
scalar field and its first derivatives, we review and extend the calculation of
the observable three-point function. We compute the "next-order" slow-roll
corrections to the bispectrum in closed form, and obtain quantitative estimates
of their magnitude in DBI and power-law k-inflation. In the DBI case our
results enable us to estimate corrections from the shape of the potential and
the warp factor: these can be of order several tens of percent. We track the
possible sources of large logarithms which can spoil ordinary perturbation
theory, and use them to obtain a general formula for the scale dependence of
the bispectrum. Our result satisfies the next-order version of Maldacena's
consistency condition and an equivalent consistency condition for the scale
dependence. We identify a new bispectrum shape available at next-order, which
is similar to a shape encountered in Galileon models. If fNL is sufficiently
large this shape may be independently detectable.Comment: v1: 37 pages, plus tables, figures and appendices. v2: supersedes
version published in JCAP; some clarifications and more detailed comparison
with earlier literature. All results unchanged. v3:improvements to some
plots; text unchange
Sorafenib for the treatment of advanced hepatocellular cancer â a UK audit
Aims:
Sorafenib is the current standard treatment for advanced hepatocellular carcinoma. We carried out a national audit of UK patients treated with sorafenib as standard-of-care and those treated with systemic therapy in first-line trials.
Materials and methods:
Sorafenib-treated and trial-treated patients were identified via the Cancer Drugs Fund and local databases. Data were collected retrospectively from medical records according to a standard case report form. The primary outcome measure was overall survival, estimated by the KaplanâMeier method.
Results:
Data were obtained for 448 sorafenib-treated patients from 15 hospitals. The median age was 68 years (range 17â89) and 75% had performance status †1. At baseline, 77% were Child-Pugh A and 16.1% Child-Pugh B; 38% were albuminâbilirubin grade 1 (ALBI-1) and 48% ALBI-2; 23% were Barcelona Clinic Liver Classification B (BCLC-B) and 72% BCLC-C. The median time on sorafenib was 3.6 months, with a mean daily dose of 590 mg. The median overall survival for 448 evaluable sorafenib-treated patients was 8.5 months. There were significant differences in overall survival comparing Child-Pugh A versus Child-Pugh B (9.5 versus 4.6 months), ALBI-1 versus ALBI-2 (12.9 versus 5.9 months) and BCLC-B versus BCLC-C (13.0 versus 8.3 months). For trial-treated patients (n = 109), the median overall survival was 8.1 months and this was not significantly different from the sorafenib-treated patients.
Conclusion:
For Child-Pugh A patients with good performance status, survival outcomes were similar to those reported in global randomised controlled trials. Patients with ALBI grade > 1, Child-Pugh B or poor performance status seem to derive limited benefit from sorafenib treatment
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