563 research outputs found
Lambda-nuclear interactions and hyperon puzzle in neutron stars
Brueckner theory is used to investigate the in-medium properties of a
-hyperon in nuclear and neutron matter, based on hyperon-nucleon
interactions derived within SU(3) chiral effective field theory (EFT). It is
shown that the resulting single-particle potential
becomes strongly repulsive for densities
of two-to-three times that of normal nuclear matter. Adding a density-dependent
effective -interaction constructed from chiral
three-body forces increases the repulsion further. Consequences of these
findings for neutron stars are discussed. It is argued that for hyperon-nuclear
interactions with properties such as those deduced from the SU(3) EFT
potentials, the onset for hyperon formation in the core of neutron stars is
expected to be shifted to extremely high baryon density, thus potentially
resolving the so-called hyperon puzzle.Comment: 6 pages, two figures; longer discussion about uncertainties adde
Weekly irinotecan in a patient with metastatic colorectal cancer on hemodialysis due to chronic renal failure
Background: The cytotoxic treatment of patients suffering from advanced or metastatic cancer undergoing hemodialysis due to chronic renal failure still remains a problem, since for those patients pharmacokinetic and pharmacodynamic data on most cytotoxic agents are lacking. Case Report: We report a 45-year-old male who suffered from chronic renal failure and was diagnosed with stage-3 colorectal cancer (CRC) in February 2000. After surgical removal of the tumor an adjuvant chemotherapy of dose-reduced i.v. bolus 5-fluorouracil and folinic acid was begun (Mayo protocol). Due to excessive gastrointestinal toxicity, therapy was discontinued after the first cycle. In April 2000 liver metastases were diagnosed. The patient was then put on a weekly schedule of dose-reduced CPT-11 (50 mg/m(2), 80 mg total). No hematological or non-hematological toxicity grade 3/4 was observed. Due to excellent tolerability and lack of severe side effects the dose was increased up to 80 mg/m2 (140 mg total) weekly. A dose escalation to 100 mg/m(2) (180 mg total) resulted in severe diarrhea (grade 4). Within 2 months of treatment the patient achieved a lasting partial remission until April 2001 (12 months). A significant progression of hepatic metastases required an alternative treatment regimen beginning in July 2001 (HAI, hepatic artery infusion). Conclusion: This case report demonstrates the feasibility and efficacy of a weekly treatment with dose-reduced CPT-11 in a patient with metastatic CRC on hemodialysis due to chronic renal failure
Kaonic hydrogen and K^- p scattering
Chiral SU(3) effective field theory in combination with a relativistic
coupled channels approach is used to perform a novel analysis of the strong
interaction shift and width in kaonic hydrogen in view of the new accurate DEAR
measurements. Questions of consistency with previous K^- p data are examined.
Coulomb and isospin breaking effects turn out to be important and are both
taken into account in this work.Comment: 4 pages, 4 figure
Vector-axialvector mixing from a chiral effective field theory at finite temperature
We study the vector-axialvector mixing in a hot medium and its evolution
toward the chiral phase transition using different symmetry restoration
scenarios based on the generalized hidden local symmetry framework. We show
that the presence of the meson reduces the vector spectral function
around meson mass and enhances it around meson mass. The coupling
strength of to and vanishes at the critical temperature due
to the degenerate - masses. This feature holds rigorously in the
chiral limit and still stays intact to good approximation for the physical pion
mass.Comment: v2:11 pages, 6 figures, reorganized and expanded the text, new plots
and references added, main result and conclusions unchange
Quasiparticle Description of Hot QCD at Finite Quark Chemical Potential
We study the extension of a phenomenologically successful quasiparticle model
that describes lattice results of the equation of state of the deconfined phase
of QCD for Tc <= T < 4 Tc, to finite quark chemical potential mu. The phase
boundary line Tc(mu), the pressure difference (p(T,mu)-p(T,mu=0))/T^4 and the
quark number density nq(T,mu)/T^3 are calculated and compared to recent lattice
results. Good agreement is found up to quark chemical potentials of order mu =
Tc.Comment: 12 pages, 7 figures; added reference
Hyperon-nucleon interaction at next-to-leading order in chiral effective field theory
Results for the Lambda N and Sigma N interactions obtained at next-to-leading
order in chiral effective field theory are reported. At the order considered
there are contributions from one- and two-pseudoscalar-meson exchange diagrams
and from four-baryon contact terms without and with two derivatives. SU(3)
flavor symmetry is imposed for constructing the hyperon-nucleon interaction
while the explicit SU(3) symmetry breaking by the physical masses of the
pseudoscalar mesons (pi, K, eta) is taken into account. An excellent
description of the hyperon-nucleon system can be achieved at next-to-leading
order. It is on the same level of quality as the one obtained by the most
advanced phenomenological hyperon-nucleon interaction models.Comment: 29 pages, 14 figures, uses elsarticle.cls and elsart3p.cl
A query suggestion workflow for life science IR-systems
Summary Information Retrieval (IR) plays a central role in the exploration and interpretation of integrated biological datasets that represent the heterogeneous ecosystem of life sciences. Here, keyword based query systems are popular user interfaces. In turn, to a large extend, the used query phrases determine the quality of the search result and the effort a scientist has to invest for query refinement. In this context, computer aided query expansion and suggestion is one of the most challenging tasks for life science information systems. Existing query front-ends support aspects like spelling correction, query refinement or query expansion. However, the majority of the front-ends only make limited use of enhanced IR algorithms to implement comprehensive and computer aided query refinement workflows. In this work, we present the design of a multi-stage query suggestion workflow and its implementation in the life science IR system LAILAPS. The presented workflow includes enhanced tokenisation, word breaking, spelling correction, query expansion and query suggestion ranking. A spelling correction benchmark with 5,401 queries and manually selected use cases for query expansion demonstrate the performance of the implemented workflow and its advantages compared with state-of-the-art systems.</jats:p
Non-Perturbative Scales in Soft Hadronic Collisions at High Energies
We investigate the role of nonperturbative quark-gluon dynamics in soft high
energy processes. In order to reproduce differential and total cross sections
for elastic proton-proton and proton-antiproton-scattering at high energy and
small momentum transfer it turns out that we need two scales, the gluonic
correlation length and a confinement scale. We find a small gluonic correlation
length, a = 0.2 fm, in accordance with recent lattice QCD results.Comment: 8 pages,latex, 2 figures uuencode
- …